Methods and apparatuses for forming an article

ABSTRACT

Methods and apparatuses are provided for depositing a material on a surface. In accordance with the method a stream of a component material is formed having formed printing and non-printing droplets and satellite droplets of the material. The stream is directed at the surface. A deflecting energy is applied to separate printing droplets from non-printing droplets in the stream, so that only printing droplets travel to the surface. The deflecting energy is adapted to direct non-printing droplets for non-printing drop collection, and to direct at least a portion of the satellite droplets to be controlled in a manner adapted to prevent the material in the satellite droplets from reaching the surface, so that less than all of the material in the satellite droplets reaches the surface. Articles are also provided having limited satellite material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 11/003,822, filed Dec. 3,2004, now U.S. Pat. No. 7,288,469.

FIELD OF THE INVENTION

This invention generally relates to a method for forming two andthree-dimensional structures using ink jet printing mechanisms and moreparticularly relates to improved methods and apparatus for web-basedfabrication of electronic or optical devices using material depositionfrom a continuous stream of printing droplets.

BACKGROUND OF THE INVENTION

It is recognized that high-speed manufacture helps to drive down thecost of a broad range of products ranging from consumable items andmaterials to electronic and optical components. Web-based fabrication,conventionally used for making photographic film and related sensitizedmaterials, is particularly advantaged for high-speed manufacture ofproducts formed on flexible substrates. Thus, methods that utilizeweb-based fabrication enable more economical manufacturing solutions forexisting products and enable the development of new products on flexiblesubstrates.

One area of particular interest for high-speed, web-based manufacturerelates to the fabrication of electronic or optical devices on flexiblesubstrates. Methods for device fabrication would form the componentelements of such electronic or optical devices by depositing patternedlayers of material, in liquid droplet form, onto a substrate. Inweb-based printing, a flexible medium, typically provided in roll or cutsheet form, is fed to the printing mechanism and is moved through theprinting mechanism during application of inks or other materials. Inconcept, web-based fabrication would adapt this printing model formanufacturing electronic and other devices on a flexible support orsubstrate. In order to fabricate electronic or optical devicescommercially onto a moving flexible substrate using liquid dropletdeposition, the following requirements are of special importance:

-   -   (i) High resolution (dots per inch). The capability for fine        detail needed to form layers within an electronic component        places high demands on droplet resolution, that is, on spatially        compact and accurate placement of droplets. Although        high-resolution can be achieved by executing multiple passes of        the receiving surface past a printing mechanism, it would be        highly preferable to deposit all droplets of a single fluid from        the same droplet forming or droplet ejection station in one pass        to form a structure. This cannot be done with conventional drop        on demand ink jet technology because such technology cannot        apply liquids with laydown densities sufficient to form many        desirable structural features in a single pass. Accordingly,        multiple passes are required to form such structures using        conventional droplet demand ink to technology. This creates the        potential for registration errors which can affect the quality        of the formed structure. Further, such an approach creates        striations within the formed structure that can alter the        performance capabilities of the structure. For example, in FIG.        1A, a cross-section view of a structure 3 is shown that is        formed using such prior art technologies. As is shown in FIG.        1A, a first layer 4 of structure 3 is formed on a substrate 2 in        a first printing pass. Similarly, second layer 5 is applied to        first layer 4 in a second pass, while a third layer 6 is applied        in a third pass. It will be appreciated that the nature of and        quality of the material boundaries between first layer 4, second        layer 5, and third layer 6 limits the functional capabilities of        structure 3 so formed. For example these boundaries, referred to        herein as striations can alter the conductance of structure 3,        the mechanical strength of structure 3, the thermal management        capability to the structure 3 or other desirable properties of        structure 3. Accordingly, what is desired is a system that is        capable of forming structures comprising a relatively large        feature height but with a minimum number of striations.        Undesirable artifacts may be visible in a top view as shown in        FIG. 1C, which is a top view the structure illustrated in        section in FIG. 1A. Such artifacts can be caused by deposition        of discrete drops too widely separated in time which, in turn,        causes registration problems.    -   (ii) Dependable delivery of fluid droplets at the needed volume        and flow rate, without interruption. Related both to resolution        and to yield percentages for a continuously moving substrate,        this requirement concerns the overall speed, reliability, and        robustness of the droplet-forming mechanism itself. Since web        fabrication uses a continuously moving substrate, there is no        opportunity to rescan an area of the substrate to ensure droplet        delivery once the substrate has moved past the droplet-ejection        station. In a single pass, it would be preferable to be able to        form a feature on a surface where the height of the feature is        relatively large. The relative height of a feature can be best        expressed in terms of a height:width ratio for the feature, as        formed by the droplet ejection mechanism in a single pass. A        height:width ratio of at least 0.20 must be achievable with the        substrate traveling at a rate of speed exceeding a few inches        per second.    -   (iii) Highly accurate droplet positioning. Also related to        resolution and yield, the positional accuracy of the        droplet-ejection mechanism must allow droplet placement accuracy        preferably within +/−2 microns. For a straight line feature        extending in any direction along the flexible substrate, height        of the feature should be controllable to within about 1% RMS.        Width should be controllable to within about 1% RMS.    -   (iv) Precision control of droplet volume. Similarly related to        resolution and yield, the stringent requirement for droplet        volume control assures that precisely the correct amount of        fluidic material is deposited at each location on the flexible        substrate surface. For electronic component fabrication, droplet        volumes would range from about 3 to about 40 picoliters, with        volume controlled to within about +/−1% or better. The        capability to change droplet volume and maintain this tight        level of control would be particularly advantageous for        component fabrication.    -   (v) Flexibility for droplet treatment, in flight and on impact.        For some types of fluid materials, it may be advantageous to        provide some type of conditioning treatment, such as to obtain        proper adhesion, for example, or to prevent or facilitate rapid        drying. This function can be most easily achieved where the        distance allowable between the droplet ejection mechanism and        the substrate surface is somewhat flexible. For a broad range of        applications, it would be advantageous to allow a gap between        the ejection point of a liquid droplet and the substrate        surface.    -   (vi) Capability to handle a range of fluid viscosities. The many        types of fluids that must be deposited for forming electronic        components and other complex devices span a wide range of        viscosities. High-viscosity fluids, in particular, such as those        with a low shear in excess of 10 cP, can prove difficult to        deposit accurately in droplet form. A number of fluid materials        with advantageous properties for forming electronic devices have        low shear viscosities in excess of 100 cP, well beyond the range        of conventional droplet deposition devices. One problem inherent        to droplet-based delivery of high viscosity fluids relates to        undesirable satellite droplets that form as a result of droplet        formation. Generally tinier than printing droplets, satellite        droplets form due to the complex rheology of these substances.

FIG. 1B shows a top view of a substrate 2 having intentionally printeddrops 7 of material adjacent to each other with undesirable satellitedrops 8 and 9 in the vicinity of the intentionally printed drops 7. Suchsatellite drops can have a number of undesirable effects on thestructure formed on substrate 2. For example, as is shown in FIG. 1B,satellite drop 8 is positioned proximate to one of the intentionallyprinted drops 7 so as to effectively alter the shape thereof. As is alsoshown in FIG. 1B, satellite drops 9 are positioned between intentionallyprinted drops 7 and can, in certain embodiments, provide an undesirableelectrical short therebetween or create other unintentional effects.

-   -   (vii) Adaptability to a range of fluid characteristics. In        addition to viscosity, there are a number of other fluid        properties that present special challenges for deposition onto a        flexible substrate in droplet form. Volatile and other        heat-sensitive fluids must be carefully handled and may not be        suitable for droplet ejection methods that employ high heat        levels. Highly viscous polymers can be particularly sensitive to        high heat levels. Fluids that exhibit electroluminescence must        also be protected from high heat conditions. The droplet        formation and ejection mechanisms would ideally be capable of        depositing both conductive and non-conductive fluids. It would        be advantageous to be able to form and eject fluid droplets        containing colloids and particulates, including fluids        containing suspended nanoparticles. In addition, it would be        beneficial to be able to adapt the deposition mechanism to the        rheology of the deposited fluid, rather than being constrained        by inherent limitations of the fluid delivery technology.    -   (viii) Suitable surface preparation. The method adapted for        fluid deposition must be compatible with various types of        surface preparation techniques for improved droplet adhesion,        spread, and related characteristics.

Conformance to the above-listed requirements is well beyond thecapabilities of conventional methods for droplet deposition. The abilityto meet or exceed these requirements would enable web-based fabricationwith increasingly faster throughput, possibly allowing web mediatransport speeds in excess of 1000 feet per minute for some types ofapplications and components.

Conventional techniques for the fabrication of electronic andelectro-optical devices typically involve a number of differentprocesses for forming various layers that make up the device, includingphotolithography, oxidation, etching, and masking, for example.Techniques for depositing materials in a droplet or vaporized form tobuild surface features include vacuum or vapor deposition, sputtering,and droplet deposition using spray bar apparatus. Often, multipleprocesses are used in combination, requiring transfer of a substratebetween various types of equipment and involving careful handling of theproduct in its intermediate fabrication stages. Because of this, thecomplex processing sequence that is currently required for fabricationof a display device or for a support electronic component such as afield effect transistor is time-consuming, trouble-prone, and costly. Asthe number of processing steps increases, the technical challenges forintegration of components on a flexible substrate become even moredemanding, throughput slows, the likelihood of contamination increases,and yields can be dramatically reduced.

Attempts to improve conventional fabrication techniques and achieve moresatisfactory yields have included use of drop-on-demand ink jet printheads for deposition of at least some layers of electronic or opticalcomponents, as is disclosed, for example, in U.S. Pat. No. 6,503,831 toSpeakman; U.S. Pat. No. 6,194,837 and U.S. Pat. No. 6,545,424 to Ozawa;U.S. Pat. No. 6,373,453 and U.S. Pat. No. 6,642,651 to Yudasaka; U.S.Pat. No. 6,555,968 to Yamazaki et al.; and U.S. Pat. No. 6,087,196 toSturm et al.

In operation, “drop-on-demand” ink jet printing provides fluid dropletsfor impact upon a recording surface using a localized pressurizationactuator (thermal, piezoelectric, air pressure, etc.) at each nozzle.Selective activation of the actuator causes the formation and ejectionof a droplet from a corresponding nozzle. The droplet crosses the spacebetween the print head nozzle and the print substrate and strikes theprint substrate. The formation of printed images, for example, isachieved by controlling the individual formation of ink droplets, as isrequired to create the desired image. With thermal actuators, a heaterfor each nozzle, located at a convenient location, heats the fluidwithin a chamber, causing a quantity of the fluid to change phase and toform a gaseous steam bubble. This momentarily increases the internalfluid pressure sufficiently for a fluid droplet to be expelled. Thebubble then collapses as the heating element cools, and the resultingvacuum draws fluid into the chamber from a reservoir to replace fluidthat was ejected from the nozzle. Alternately, piezoelectric actuators,such as that disclosed in U.S. Pat. No. 5,224,843 to vanLintel, have apiezoelectric crystal in a fluid channel that flexes when an electriccurrent flows through it, forcing a fluid droplet out of a nozzle.

In conventional thin-film fabrication methods, such as those used incommercially available drop-on-demand ink jet printers, a sheet ofsubstrate is held stationary during materials deposition. One or moreprint heads or other printing mechanisms are then passed over thestationary substrate, one or more times, in order to deposit the variouscomponent layers with sufficient resolution to form the electronicdevice. Once deposition of these materials is complete, the sheet ofsubstrate can be lifted from place and made available for any furtherprocessing.

However, while drop-on-demand ink jet print mechanisms have been adaptedfor depositing some types of materials onto a substrate, there aresignificant drawbacks and performance thresholds, inherent todrop-on-demand technology, that limit its usefulness for web-basedfabrication of electronic and related components, in which the substrateis continuously moving. The resolution limitations of drop-on-demandprinters are a function of the droplet formation and delivery,componentry design, with a separate heater or piezoelectric actuatorrequired for each individual nozzle. Characteristically, drop-on-demandprinters improve their inherently low resolution by making a series ofrepeated passes over the same area of a substrate. The use of repeatedpasses, however, would not be well-suited to a web manufacturingenvironment with a continuously moving substrate. In addition, layeringof the same material onto itself in successive passes is not optimal forobtaining homogeneous density. For most deposited materials, striationsdevelop at the interface between successively printed layers, which isundesirable in many applications, for example in the deposition ofOrganic Light Emitting Diode (OLED) or Polymeric Light Emitting Diode(PLED) materials.

Droplet volume control is typically well above +/−5% at best, alimitation that is further compounded by tendency of nozzles to clog orto form and eject unwanted satellite droplets. There is no known methodfor compensating for the formation of satellite droplets that candeposit material improperly, compromising component operation or evencausing component failure. Satellite droplets are commonly observed withdrop-on-demand print devices, particularly where fluids deposited exceedviscosities of about 3 cP. The viscosity range of drop-on-demandprinters is very limited; high viscosity fluids can exhibit low-shearviscosities well out of range of accurate droplet formation and deliveryfor these devices. Because many types of drop-on-demand print headsemploy pulsed heat for forming and ejecting droplets, there are alsolimitations on the types of fluids that can be accurately deliveredwithout being damaged or introducing safety problems. Requiring a closeproximity between the nozzle and receiving substrate, the drop-on-demandprint head is relatively inflexible for allowing supporting dropletconditioning mechanisms to be used. Drop-on-demand print mechanismscannot be scaled, beyond a narrow range, to suit the rheology of thefluid to be deposited; instead, the fluid must be adapted to the fairlylimited geometry of the drop-on-demand droplet forming mechanism.

To counter some of the inherent limitations of this technology, sometypes of drop-on-demand solutions use a wax carrier into which acolorant or dye is mixed. For this type of print technology, the waxcarrier remains as part of the deposited material. While this may beacceptable for some types of color printing, it can be readilyappreciated that the retention of a wax carrier would prevent componentfabrication in most cases. Finally, while the quality of patterns formedusing drop-on-demand ink jet techniques can be acceptable at lowerthroughput rates where the substrate can be held stationary, the demandsof web fabrication at high rates of speed easily exceed the capabilitiesof drop-on-demand technology and restrict the types of components thatcan be fabricated or require combination with other types of depositionmethods to supplement the droplet formation provided from the printhead.

Recognizing the shortcomings of conventional inkjet printing forcomponent fabrication, a number of hybrid methods have been proposed.These include methods disclosed in the Ozawa '837 and '424 patents citedabove, in which, for a device comprising multiple layers of material,some of the component layers are deposited using drop-on-demand ink jetprinting and other layers are deposited using vacuum deposition or othermethods, including conventional use of masks and photochemical etching,as is described in International Application WO 97/18944 by Calvert etal.; European Patent EP 0 615 256 to Mutsaers et al.; European PatentApplication EP 1 079 397 to Cloots et al.; and U.S. Pat. No. 5,976,284to Calvert et al. However, it can be appreciated that such hybridmethods are not particularly conducive to high-speed web-basedfabrication and add cost and complexity to the fabrication process. Asis true with conventional photo-etching schemes, the substrate itselfmust be maintained in place during the deposition process, effectivelyprecluding any type of web-based fabrication. Given the constraintsinherent to conventional drop-on-demand ink jet print apparatus, itwould be difficult to further extend the use of drop-on-demand ink jetmasking technology for forming conductive patterns of higher complexityand high resolution and to obtain the economies of high-speed productionafforded by web-based fabrication.

Increasing demand for economical, high-speed methods of fabrication forelectronic, electro-optical, or optical devices, particularly forOrganic Light Emitting Diodes (OLED) and Polymeric Light Emitting Diodes(PLED) sometimes known as solution processable organic light emittingdiode display components, points to the need for improvements over theconventional fabrication methods that have been commercialized to date.Thus, it can be seen that there is a need for an improved method andapparatus for forming two- and three-dimensional structures on flexiblesubstrates using web-based fabrication techniques, in which thesubstrate is continuously moving in a travel direction.

SUMMARY OF THE INVENTION

Methods and apparatuses are provided for depositing a material on asurface. In accordance with one embodiment of the method a stream of acomponent material is formed having formed printing and non-printingdroplets and satellite droplets of the material. The stream is directedat the surface. A deflecting energy is applied to separate printingdroplets from non-printing droplets in the stream, so that only printingdroplets travel to the surface. The deflecting energy is adapted todirect non-printing droplets for non-printing drop collection, and todirect at least a portion of the satellite droplets to be controlled ina manner adapted to prevent the material in the satellite droplets fromreaching the surface, so that less than all of the material in thesatellite droplets reaches the surface. Articles are also providedhaving limited satellite material.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter of the present invention, itis believed that the invention will be better understood from thefollowing description when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1A shows a cross section view of a structure formed on a substrateusing multiple printing passes as is known in the prior art;

FIG. 1B shows a top view of a substrate having intentionally printeddrops of material adjacent to each other with undesirable satellitedrops formed in accordance with the prior art;

FIG. 1C which is a top view of the structure illustrated in section inFIG. 1A;

FIG. 2A is a perspective block diagram view of an existing apparatus forprinting using a continuous ink jet print head;

FIG. 2B is a side view schematic block diagram showing a web fabricationapparatus using a continuous ink jet print head adapted according to thepresent invention;

FIG. 2C is a side view schematic block diagram showing a web fabricationapparatus that uses multiple arrays of nozzles for emitting dropletstreams;

Referring to FIG. 3, there is shown a nozzle of a continuous ink jetprint head with electrodes that provide electrostatic deflection ofdroplets in a stream;

FIG. 4 is a close-up cutaway side view showing a single nozzle of animproved type of continuous ink jet print head using gas flow toselectively deflect droplets for printing;

FIG. 5A is a close-up cutaway side view showing a single nozzle of acontinuous ink jet print head adapted according to the presentinvention, with added gutter, shielding, and collection structures forboth non-printing and satellite droplets;

FIG. 5B is a close-up cutaway side view showing a single nozzle of thecontinuous ink jet print head 4 adapted according to another embodimentof the present invention, with added gutter, shielding, collection, andrecycling structures for both non-printing and satellite droplets;

FIG. 5C is a close-up cutaway side view showing a single nozzle of thecontinuous ink jet print head adapted according to still anotheralternate embodiment of the present invention, with added gutter,shielding, collection, and recycling structures for both non-printingand satellite droplets, wherein diverted droplets are directed to thesupport;

FIGS. 6A and 6B are cross-sectional views of a transistor fabricatedusing the methods and apparatus of the present invention;

FIG. 7 shows a plane view of a mask deposited using selective dropletdeposition from a continuous stream of droplets according to the presentinvention;

FIG. 8 shows a side view in cross-section of an arrangement of masksections in one embodiment;

FIG. 9A shows a cross-section of a display pixel fabricated using themethods and apparatus of the present invention;

FIG. 9B shows a cross-sectional view of a display pixel and switch;

FIG. 10 shows a side view in cross-section of an OLED device havingbarrier coatings deposited according to the present invention; and

FIG. 11 shows a top view of a section of an article having a printeddroplet within an area also containing a satellite droplet;

FIG. 12 shows a top view of section of another embodiment of an articlehaving a linear pattern of printed droplets within an area alsocontaining a satellite droplet;

FIG. 13 shows a top view of a section of another embodiment of anarticle having a block pattern of printed droplet within an area alsocontaining a satellite droplet;

FIG. 14 shows a top view of a section of another embodiment of anarticle of the invention; and

FIG. 15 shows still another top view of a section of another embodimentof an article of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present description is directed in particular to elements formingpart of, or cooperating more directly with, apparatus in accordance withthe invention. It is to be understood that elements not specificallyshown or described may take various forms well known to those skilled inthe art.

Continuous ink jet print heads have been used in a number of differenttypes of large format, high-quality color printing apparatus. Thecontinuous ink jet printing technology itself is not new. U.S. Pat. No.1,941,001, issued to Hansell on Dec. 26, 1933, and U.S. Pat. No.3,373,437, issued to Sweet et al. on Mar. 12, 1968, each discloseprinting apparatus using an array of ink jet nozzles wherein inkdroplets to be printed are selectively charged and deflected towards arecording medium. This early droplet steering technique described in the'001 (Hansell) and '437 (Sweet et al.) patents is known as binarydeflection continuous ink jet. Unlike drop-on-demand devices, continuousink jet printers operate by generating a continuous sequence of inkdroplets in a stream directed toward the receiving surface andselectively steering individual ink droplets along either of twotrajectories: droplets along one trajectory are directed onto therecording surface for imaging; droplets along the other trajectory arenon-printing droplets, diverted from the surface and typically recycled.

A continuous ink jet printer forms the droplet stream using apressurized ink source that is separate from the nozzle assembly itself.A number of different types of droplet steering mechanisms have beendeveloped for these devices. Conventional continuous ink jet printerssteer droplets from the droplet stream utilizing electrostatic chargingdevices that are placed close to the point where a filament of ink froma nozzle breaks into individual ink droplets. The ink droplets areelectrically charged and are then directed along the appropriatetrajectory using deflection electrodes. When no printing droplet isneeded, the ink droplets are directed along the waste trajectory into anink-capturing mechanism (often referred to as a catcher, interceptor, orgutter). When a print droplet is desired, the ink droplet is directedalong the print trajectory, substantially normal to the receivingsurface of a recording medium, to strike the recording medium at aspecific location.

Printing Apparatus Using Continuous Ink Jet Print Head

Referring to the block diagram of FIG. 2A, there is shown an embodimentof a print apparatus 10 using a continuous ink jet print head 12 fordepositing ink onto a print support 14. In one embodiment, support 14 isprovided on a moving web; however, only that portion of print support 14in the vicinity of continuous ink jet print head 12 is represented inFIGS. 2A and 2B. Referring to FIG. 2A, printing apparatus 10 includes apattern source 16 such as a scanner or computer which provides digitalimage pattern data for forming a pattern of ink onto support 14. Thisimage data is converted to droplet pattern data by an image patternprocessing unit 18 which also stores the image data in memory. Aplurality of heater control circuits 20 read data from the image memoryand apply time-varying electrical pulses to a set of nozzle heaters 22that are part of continuous ink jet print head 12. These pulses areapplied at an appropriate time, and to the appropriate nozzle, so thatdrops formed in the droplet stream are deposited onto support 14 in theappropriate position designated by the image data in memory, therebyforming the printed image.

As indicated by the directional arrow in FIG. 2A, support 14 is moved ina travel direction relative to print head 12 by support transport system24, which is electronically controlled by a transport control system 26,and which in turn is controlled by a micro-controller 28. Supporttransport system 24 shown in FIG. 2A is a schematic representation only,and many different mechanical configurations are possible. For example,a combination of drive rollers and intermediate transfer rollers couldbe used to facilitate transport of support 14. An intermediate transferroller or other conventional coating methods could be used to apply amaterial treatment onto support 14 for conditioning the surface prior toor following deposition by continuous ink jet print head 12, usingtechniques well known in the ink jet imaging arts. A range of mediatransport speeds is possible, depending on factors such as materialsdeposited, support type and surface treatment, and media width.

Referring again to FIG. 2A, the deposited ink is provided from a fluidreservoir 30, under pressure. In the non-printing state, droplets areunable to reach support 14 due to a fluid gutter 17 that blocks thestream and which typically allows a portion of the ink to be recycled bya fluid recycling unit 19. Fluid recycling unit 19 reconditions the inkand feeds it back to fluid reservoir 30, using techniques well known inthe art. The ink fluid pressure suitable for optimal operation dependson a number of factors, including geometry and thermal properties of thenozzles and viscosity and thermal properties of the ink. A constantfluid pressure can be achieved by applying pressure to fluid reservoir30 under the control of fluid pressure regulator 32.

The fluid ink is distributed to the back surface of print head 12 andpreferably flows through slots and/or holes etched through a siliconsupport of continuous ink jet print head 12 to its front surface, wherea plurality of nozzles and heaters are situated. With continuous ink jetprint head 12 fabricated from silicon, it is possible to integrateheater control circuits 20 with the print head.

Typically, continuous ink jet printing devices shown in FIGS. 2A and 2Bare capable of faster printing than are drop-on-demand ink jet printingdevices and are preferred where higher quality printed images andgraphics are needed. However, for reasons described below, continuousink jet printing devices have not been widely used for applicationsother than high-value color printing and prepress environments.

The potential of continuous ink jet printing technology has not beentapped for fabrication of electronic or optical components and forforming other 2-D and 3-D structures on a support for a number ofreasons. In general, continuous ink jet printers can be more complexthan drop-on-demand printers, since each fluid that is printed requiresan individual droplet formation, deflection, and waste capturing system.Because conventional continuous ink jet printers utilize electrostaticcharge for droplet deflection, these devices would not provide asuitable mechanism for depositing fluids that are insulators, forexample. Moreover, requirements for waste fluid recycling andmanagement, problems with the overall availability of print heads usingthis alternative technology, and unfamiliarity with the requirements andcontrol of this alternative technology appear to have discouragedresearchers from employing continuous ink jet methods for fabrication ofOLED, PLED, and other electronic and optical devices.

Conventional continuous flow print head technology employs electrostaticforces for droplet steering, providing selective deflection of dropletsin the stream emitted from each nozzle. Referring to FIG. 3, there isshown a nozzle 44 of a continuous ink jet print head 12 with electrodes40 that provide electrostatic deflection of droplets 38 in stream 36.Nozzle 44 emits a flow 46 that breaks into a succession of droplets 38,with droplets 38 following each other in rapid succession. A gutter 42acts as a type of receiving area, collecting deflected droplets 39 byelectrodes 40; undeflected droplets 43 are deposited on support 14. Itmust be observed that either the deflected droplets or the undeflecteddroplets 43 can be deposited, depending on the configuration of printhead 12.

A potential advantage of continuous ink jet printing relates to thecapability for precision control of fluid droplet volume. Methods forselective droplet deposition from a continuous stream of droplets allowcontrol of droplet size to well within +/−1.0% nozzle-to-nozzle withmost fluids. This added control is one factor that allows continuous inkjet printing, for example, to enjoy higher resolution and more accuratedroplet placement than is available using alternative types ofdroplet-ejection devices.

Yet another potential advantage of using selective droplet depositionfrom a continuous stream of droplets is that the nozzle-to-supportdistance is substantially larger than is available for drop-on-demandink jet or other types of deposition methods. Because fluid pressure isprovided separately from the nozzle array, the continuous stream nozzlecan be greater than a few millimeters from the support surface for mostfluids. This allows space for droplet or surface conditioningimmediately before, during, or immediately following droplet travel.This also makes it possible for multiple nozzle structures to bedirected toward the same point or line along the support, allowing agreater range of fluid volumes to be deposited.

The droplet frequency formed by selective droplet deposition from acontinuous stream of droplets can be several times that of conventionaldrop-on-demand print heads or of other droplet deposition mechanisms.This inherent high droplet formation frequency not only allows multipleprint nozzles to be directed toward the same point on the support, butalso allows multiple drops to be overlaid before any significant dryingor curing occurs, thereby minimizing undesirable striations in adeposited feature. This advantage can be particularly contrasted withdrop-on-demand and other droplet deposition methods, where there aremultiple passes required to obtain sufficient depth of material,resulting in striations at the interfaces between layers.

The employment of selective droplet deposition from a continuous streamof droplets allows the use of a number of different possible diluentcarrier fluids into which the deposited material is mixed. Types ofdiluent carriers available include organic solvents, for example. Unlikewaxes used with phase change drop-on-demand print mechanisms, thecarrier used for continuous stream droplet deposition can be dried oncethe droplet is deposited. Only trace amounts (for example, less than 1%by volume) of the carrier would remain once the droplet is dried.

Although conventional electrostatic continuous flow ink jet technologyhas advantages for printing color inks, there are some inherentshortcomings of this technology that constrain its adaptation for use infabricating components. As one drawback, the conductivity range formaterials ejected from continuous ink jet print heads usingelectrostatic deflection is typically from about 500 to about 2,000microsiemens/cm. This limits the usability of electrostatic deflectionmethods for non-conductive materials and prevents the use of thistechnology for depositing insulators within a component or circuit.Further, the combination of electrostatic deflection and acousticstimulation as is known in the art is capable only over a limitedviscosity range. Most color inks deposited using this technology haveNewtonian viscosities within 1-2 cP. However, many of the liquidmaterials needed for component fabrication have much higher viscosities,many in excess of 10 cP, some that show shear thinning rheologies.

A further problem with electrostatic deflection from the continuousstream of droplets relates to satellite droplets. FIG. 3 shows droplets38 in stream 36, directed toward the surface of support 14, wheredeflected droplets 39 travel away from the printing path. Satellitedroplets 48, typically tinier than droplets 38 and typically notsynchronous with the timing of successive droplets 38, tend to collecton structures of electrodes 40, eventually causing clogging or shortingif nozzles are not regularly cleaned. In this way, conventionalcontinuous electrostatic ink jet technology suffers from the samedrawbacks noted in the background section above for drop-on-demand inkjet printing, in which satellite droplets are generally inevitable,particularly with fluids in higher viscosity ranges. In practice, due tothe nozzle and electrode geometry of the conventional continuous flowink jet print head, satellite droplets may even pose a larger constraintfor conventional electrostatic continuous ink jet print heads used incomponent fabrication than for drop-on-demand print heads. Because ofthis susceptibility to clogging due to satellite droplets, then,conventional continuous ink jet print apparatus may not provide asufficiently robust solution for web-based electronic componentfabrication.

In one alternative embodiment, magnetic forces can be used to causeselective deflection of appropriate material.

Depositing Highly Viscous Fluids

As noted in the background section above, highly viscous fluids haveproved particularly troublesome for conventional droplet ejectionapparatus. The drop-on-demand method that is conventionally used appliesenergy, in the form of heat or pressure, to force individual dropletsfrom a meniscus formed at each nozzle. However, many highly viscousfluids exhibit high-low shear viscosity, with values ranging from 5 to10,000 centipoise (cP) for example. A number of conductive andphotoemissive polymers have viscosities in this range. Applying theneeded heat energy for phase change of these materials may causeexcessive spattering, satellite drops, or clogging in a conventionaldrop-on-demand or conventional electrostatic continuous ink jet printhead. As noted in the background section hereinabove, these tendenciesreduce droplet placement accuracy, size, and resolution and haveconstrained the usability of such highly viscous fluids for ink jetdeposition.

As has also been described above, continuous ink jet print heads operatein a very different manner from drop-on-demand print heads with respectto fluid handling. Because the continuous ink jet print head operates bysteering fluid droplets from a continuously flowing stream or series ofdroplets, forced under fluid pressure, this type of print head enjoys ashear thinning effect on highly viscous fluids. That is, once a highlyviscous fluid begins to flow, its viscosity is dramatically lowered,yielding an effective viscosity, for droplet formation, that can easilybe a few orders of magnitude below the viscosity of the stationaryfluid. This inherent difference in fluid handling at the nozzle givescontinuous ink jet printing an advantage over other droplet-formingmechanisms, such as drop-on-demand devices that induce a phase change toform droplets. As a result, highly viscous fluids such as polymers usedfor PLED fabrication and for forming conductive traces and electrodes,fluids that may easily prove out of range for conventionaldrop-on-demand printing, could be usable with methods that depositdroplets from a continuous stream of printing droplets, such as in acontinuous ink jet print head, and can be deposited with precise dropletvolume control and placement accuracy, providing high resolution.

A number of developments have improved both the method of fluid dropletformation and methods for droplet deflection for continuous flow ink jetprinting. For example, U.S. Pat. No. 3,709,432, issued to Robertson onJan. 9, 1973, discloses a method and apparatus for stimulating afilament of working fluid causing the working fluid to break up intouniformly spaced ink droplets through the use of transducers. Thelengths of the filaments before they break up into ink droplets areregulated by controlling the stimulation energy supplied to thetransducers, with high amplitude stimulation resulting in shortfilaments and low amplitude stimulation resulting in longer filaments. Aflow of air is generated across the paths of the fluid at a pointintermediate to the ends of the long and short filaments. The air flowaffects the trajectories of the filaments before they break up intodroplets more than it affects the trajectories of the ink dropletsthemselves. By controlling the lengths of the filaments, thetrajectories of the ink droplets can be controlled, or switched from onepath to another. As such, some ink droplets may be directed into acatcher while allowing other ink droplets to be applied to a receivingmember.

Referring to FIG. 4, there is shown another type of continuous ink jetprinting head. Commonly assigned U.S. Pat. No. 6,517,197, issued toHawkins et al. on Feb. 11, 2003, discloses a continuous ink jet nozzle52 that uses actuation of asymmetric heaters 54 to form individual fluiddroplets 56, 58 from a flow 60 of fluid 51 and applies a gas pressuredifferential as the deflection force 62 for fluid droplets. A print head50 includes a pressurized fluid supply 64 having fluid 51 comprising acarrier fluid having a material therein and asymmetric heaters 54operable to form printed fluid droplets 56 and non-printed fluiddroplets 58. Printed droplets 56 flow along a printed fluid droplet pathX, generally normal to the receiving medium surface, wherein the path X,in practice, is slightly shifted by force 62 to take path Z as shown inFIG. 4, ultimately striking a receiving medium, while non-printed fluiddroplets 58 flow along a non-printed fluid droplet path Y ultimatelystriking a gutter or catcher surface (not shown in FIG. 4). Non-printedfluid droplets 58 are recycled or disposed of using the catcher.

Variations and improvements to this type of continuous ink jet printerare disclosed in a number of commonly assigned patents, including thefollowing:

-   -   Commonly assigned U.S. Pat. No. 6,588,888, (Jeanmaire et al.)        discloses a continuous ink jet printer capable of forming        droplets of different size and with a droplet deflector system        for providing a variable droplet deflection for printing and        non-printing droplets;    -   Commonly assigned U.S. Pat. No. 6,491,362 (Jeanmaire) discloses        an apparatus and method for varying print drop size in a        continuous ink jet printer to allow a variable amount of droplet        deflection in the fast scan direction with multiple droplets per        pixel;    -   Commonly assigned U.S. Pat. No. 6,213,595 (Anagnostopoulos et        al.) discloses a continuous ink jet apparatus and method that        provides ink filament steering at an angle offset from normal        using segmented heaters;    -   Commonly assigned U.S. Pat. No. 6,508,543 (Hawkins et al.)        discloses a continuous ink jet print head capable of displacing        printing droplets at a slight angular displacement relative to        the length of the nozzle array, using a positive or negative air        pressure;    -   Commonly assigned U.S. Pat. No. 6,572,222 (Hawkins et al.)        similarly discloses use of variable air pressure for deflecting        groups of droplets to correct placement in the fast scan        direction; and    -   Commonly assigned U.S. Patent Application Publication No.        2003/0174190 (Jeanmaire) discloses improved measurement and fast        scan correction for a continuous ink jet printer using air flow        and variable droplet volume; and    -   Commonly assigned U.S. Pat. No. 6,575,566 (Jeanmaire et al.)        discloses further adaptations for improved print droplet        discrimination and placement using variable air flow for each        ink jet stream.

For electronic device fabrication in particular, the improved continuousstream ink jet print head described in the commonly assigned Hawkins etal. '197 patent offers a number of advantages over earlier continuousink jet print head designs that employ electrostatic deflection fordroplet steering, as was shown in FIG. 3. Significantly, because it usesgas pressure differential (optionally assisted by heat application) fordroplet steering, the continuous stream print head described in thecommonly assigned Hawkins et al. '197 patent is capable of depositinginsulator materials as well as conductive materials. Because it employsa directed differential gas pressure for stream deflection, thecontinuous stream print head described in the commonly assigned Hawkinset al. '197 patent enables the matching of suitable gases to thedeposited material, either for conditioning droplets along theirtrajectory, for conditioning “waste” droplets for eventual recycling andreuse in the printing apparatus, or for providing a controlledenvironment for droplet travel, such as using an inert gas to protectthe droplet from contamination, oxidation, or other effects. Thecontinuous ink jet print head that uses gas flow differential fordirecting droplet trajectory is advantaged both for its capability tocondition printed fluid droplets 56 (FIG. 4) in their trajectory pathand for its capability to condition the surface to which printed fluiddroplets 56 are directed. The gas flow may condition the fluid or thereceiving surface by employing an inert gas, a vapor, a heated airsource, or some other treatment, for example. Thus, in addition tosteering printed fluid droplets 56, gas flow could also provide thisadditional conditioning function.

Droplet size can be easily managed, as well as precise droplet positionand ejection timing. In addition, ink jet nozzles can be tightly spacedwhen using the continuous stream print head described in the commonlyassigned Hawkins et al. '197 patent, allowing high resolution andprecision placement.

The capability of the improved continuous ink jet print head that usesgas flow for directing droplet trajectory also proves to be particularlyadvantageous where purity of deposited materials is important. Forphotoemissive polymers, for example, there is no need to add salts orother impurities to the polymer fluid to aid in conductivity forelectrostatic deflection. Such additives could compromise polymerperformance, flexibility, and/or adhesion properties.

The capability for forming droplets of different sizes, as disclosed inthe '888 Jeanmaire et al. patent, is a particular advantage availablefrom continuous ink jet technology. This capability allows deposition ofexacting amounts of material from each nozzle, allowing features to beformed on the support with high throughput and with a high degree ofdimensional accuracy.

These notable advantages over conventional drop-on-demand technologywould make continuous ink jet printing particularly attractive fordepositing material onto a quickly moving support in a web fabricationenvironment. However, as is described subsequently, some adaptation ofexisting continuous ink jet printing methods is needed in order to makethis technology usable for component fabrication.

Yet another type of droplet deposition device that may be advantaged forcomponent fabrication in various embodiments is the continuous ink jetprint head disclosed in commonly assigned U.S. Pat. Nos. 6,474,795 and6,695,440, entitled “Continuous Ink Jet Printer with Micro-ValveDeflection Mechanism and Method of Controlling Same” to Lebens et al.The apparatus described in the Lebens et al. '795 and '440 disclosuresemploys valve mechanisms to direct ink jet flow at each nozzle. That is,the continuous ink jet printer disclosed by Lebens et al. employs adifferential fluid pressure for directing the flow of a stream of inkdroplets.

In summary, continuous ink jet printing operates by emitting, from eachnozzle in an array, a continuous series or stream of fluid droplets andby selectively steering one or more droplets from this series toward thesupport. The fluid is supplied to each nozzle under pressure, withvarious types of mechanisms provided for forming and directing thedroplet stream from the pressurized fluid and for selective deflectionof individual droplets from the droplet stream. Previously dedicated tohigh-quality color printing applications, the continuous ink jet methodof droplet deposition enjoys a number of inherent advantages over othermethods of droplet deposition for other types of fluidic materials.Because it generates and manipulates a continuous stream of tinydroplets, the continuous ink jet method provides a higher dropletfrequency than other droplet deposition methods and is capable of bothhigh resolution and high volume delivery. Thus, unlike other types ofdroplet deposition devices that require a support 14 to be rigidly heldin position as material is deposited, continuous ink jet print apparatuscan be adapted for forming surface features used in the fabrication ofelectronic, display, and optical components onto a continuously movingsupport 14.

However, the demanding requirements for handling fluids having a widerange of viscosities and for preventing the deposition of satellitedroplets that are inevitably generated during droplet formation indicatethat some amount of adaptation of continuous ink jet printing methods isnecessary in order to use these devices in a web-based componentfabrication apparatus.

Adapting Droplet Stream Technology to Web-Based Component Formation

In light of the above-noted technical hurdles and limitations, it can beseen that the type of droplet stream technology generally used forcontinuous ink jet printing has inherent advantages for accuratedelivery of a wide range of fluids onto a moving support 14. No otherdroplet formation technology offers the capability for accuracy,high-volume delivery, and range of fluid types that are potentiallyavailable using a generated stream of droplets. However, a number ofproblems need to be solved for adapting this technology to componentfabrication.

Among the inherent problems of any droplet-forming method has been theproblem of satellite droplet formation. As was noted in the backgroundsection above, drop-on-demand ink jet print heads particularly sufferfrom this droplet formation anomaly, which severely constrains theusability of that type of technology for high-density componentfabrication. Similarly, conventional electrostatic ink jet print headsare susceptible to clogging due to satellite droplet generation. Themore recent continuous ink jet print head technology of the Hawkins etal. '197 disclosure using gas differential deflection typically alsogenerates some percentage of unwanted satellite droplets 48 as shown inFIG. 4, which can be emitted onto the support 14.

Referring to FIG. 11, there is shown a plan view of printed droplet 56deposited at its intended location on the support 132. Unwantedsatellite droplets 48 have also been deposited on the support 132. Usingthe apparatus and methods of the present invention, the density ofsatellite droplets can be reduced to an average of no more than onesatellite droplet 48 within the area of a circle centered at printeddroplet 56 and three times the radius R of printed droplet 56.

FIG. 5A is a close-up cutaway side view showing a single nozzle of thecontinuous ink jet print head adapted according to the presentinvention, with added gutter, shielding, and collection structures forboth non-printing and satellite droplets. As shown in FIG. 5A, there isan arrangement of a satellite droplet guttering system 78 for nozzle 52,for suppressing the emission of satellite droplets 48 in a configurationusing gas differential deflection. Satellite droplets 48 are blocked bya shielding element 68 that cooperates with gutter 17 to collect bothsatellite droplets 48 and non-printed droplets 58 as waste for possiblerecycling. Diverted fluid droplets 67 are directed to a collectionvessel 66 for recycling, reconstitution, or disposal. In one embodiment,satellite droplet control surface 68 is a stainless steel baffledisposed near the output of print head 50.

Shielding element 68 may be coated for optimal performance, such as toprevent or delay drying of satellite drops 48 thereon. Suitable coatingscould be selected from various types of materials exhibiting lowsurface-energy properties, such as Teflon coatings, self-assembledmonolayers consisting of organothiol compounds on gold-coated surfaces,or alkoxysilanes on metal oxide surfaces, such as on silicon oxide, forexample. An active rinsing mechanism (not shown) could optionally bedeployed for wetting surfaces of shielding element 68, gutter 17, andrelated structures to prevent or delay drying. A rinsing mechanism wouldtypically apply a solvent solution of some type, suitable for the fluidbeing deposited. FIG. 5B shows an alternate embodiment in whichsatellite droplet guttering system 78 components either direct divertedfluid droplets 67 back to fluid source 64 or to an optionalreconstitution vessel 69 for reformulation. Of course, separateguttering components could be used for non-printed droplets 58 andsatellite droplets 48, so that, for example, only on the largernon-printed droplets 58 are recycled.

Referring to FIG. 5C, there is shown an embodiment in which printeddroplets 56 are diverted. With this embodiment, the arrangement ofsatellite droplet guttering system 78 can be suitably altered so thatboth non-printed droplets 58 and satellite droplets 48 are directed tocollection vessel 66 or so that these droplets are otherwise separatelycollected.

Another problem not solved using conventional droplet formation methodsis adaptation to the rheology of the fluid(s) to be deposited. Nozzle 52and its support structures can be scaled to form a stream of droplets ofsuitable size for the fluid and for fluid volumes being deposited.

A further adaptation to surmount limitations of volume delivery rangerelates to the capability to deliver fluid from multiple nozzles 52simultaneously to the same point on the support 14. This capability is aresult of the flexibility allowable in distance between nozzle 52 andthe support 14 surface. Using such a technique, volume delivery ofdroplet stream technology, already advantaged over other dropletdeposition methods, can be effectively doubled, or even furtherincreased.

Fabrication Apparatus

For overall component fabrication, the basic set of components ofprinting apparatus 10 in FIG. 2A would be similarly required ascomponents of a fabrication system. FIG. 2B shows that portion of afabrication apparatus 11 that is directly related to depositingdroplets. A continuous ink jet print head 13, adapted from continuousink jet print head 12 in FIG. 1, employs an array of printing nozzlesspecially configured for depositing fluids used in componentmanufacture. Support 14 is driven continuously in the direction of thearrow by a support transport system including in this embodiment atransport roller 14 and a transport roller driving system (not shown)such as a motor and appropriate control electronics. FIG. 2B also showsa droplet-conditioning device 34 for applying conditioning energy, insome form, to droplet stream 36. This conditioning energy can be anelectromagnetic energy such as light or other radiation. Alternately,conditioning can be performed using a gas or vapor, which can also beintroduced using the droplet deflection mechanism, such as the gas flowdescribed subsequently.

Referring to the schematic side view representation of FIG. 2C, there isshown an alternate embodiment of fabrication apparatus 11 in whichmultiple adapted continuous ink jet print heads 13 a, 13 b, and 13 c areused to deposit droplets from streams 36 of different fluids frommultiple reservoirs 30 a, 30 b, and 30 c respectively. It can beappreciated that fabrication apparatus 11 can have any of a number ofdifferent embodiments for depositing any number of fluids onto thesurface of moving support 14. Of course, this could include multiplebanks of print heads 13 depositing the same fluid, or different fluids,onto support 14.

As shown in FIG. 2C, it is possible to adjust the direction of nozzlesin adapted continuous ink jet print heads 13 a, 13 b, and 13 c, suchthat two or more nozzles effectively deposit droplets onto the samepoint on the surface of support 14 at the same time. This advantage isavailable due to the nature of droplet formation using continuous flowtechnology and due to the capability to adjust spacing of printingnozzles from support 14 over a range of distances without loss ofperformance.

Options for Support Types

Support 14 itself could be any of a number of types of material,including flexible support 14 material that can be transported as a web.A suitable flexible support 14 material for electronic and displaycomponents could be polyethylene-terephthalate (PET), polyethylenenapthalate (PEN), cellulose acetate, metal foil, aluminum or titaniumfoil, aluminum or titanium alloys, paper, steel including stainlesssteel, polyvinyl chloride (PVC), polycarbonate, polyimides, glass, andtextiles or other types of woven fabric, as disclosed in U.S. PatentApplication Publication No. 2004/0053431 entitled “Method of forming aflexible thin film transistor display device with a metal foil support”by Chang et al., for example. Other types of flexible support 14 couldbe used for a range of alternate applications.

Other types of support 14 s suitable for various applications includeborosilicate glass, polyethylene, acrylate sheeting, PVC sheeting,polycarbonate sheeting, foams, felt, fiber-reinforced epoxy, PMMA,PCB's, silicon, GaAs, and LiNbO₃ crystals, thin film membrane [siliconcompound, SiO₂, SiC, Si₃N₄, etc.], or thermoplastics such as nylon, forexample. Yet other types of supports 14 included filled polymer supports14, such as carbon-fiber filled thermoplastics and voided supports 14.

In another embodiment, support 14 could be a transfer material such as adonor that serves as an intermediate for transfer of component materialdeposited on its surface onto the surface of a different support 14.

Techniques for Forming Electronic or Optical Devices

The present invention uses a continuously generated stream of printingdroplets to deposit one or more fluids that coalesce on a surface and,when suitably dried, form a three-dimensional feature comprising atleast one, but preferably most or all of the elements necessary to forman electronic device or optical component, such as a waveguide, photonicbandgap component, lens or lenslet array, or optical coating. In orderto form electronic and optical devices with suitable efficiency andyield, environmental conditions such as temperature, humidity, andexposure to light or oxygen must be controlled and cleanlinessmaintained.

In general, the structure of an electronic device should be designed tofacilitate good interfacial reaction between its composite layers, withno striations within any single composite layer. Suitable liquids thatcan be deposited for conductive, semiconductive, insulating, andopto-electronic functions include, but are not limited to, inorganics,organics, hybridized inorganic-organic systems, and polymer-basedmaterials compatible with conventional evaporation or radiation enhanceddrying, low temperature crystallization, annealing, or curing, andradiation cross-linking or chemical bond scission or reformation.

For depositing polymer layers, fundamental properties of ideal surfacesinclude the following:

-   -   (i) The polymer surface can range from partially polycrystalline        to amorphous. With the exception of polydiacetylenes, single        crystal polymer surfaces are essentially unknown.    -   (ii) Light emitting polymers tend to be large, flexible,        covalently bonded chains. Polymer surfaces generally consist of        gently curved sections of polymer chains, with occasional chain        ends. The polymer chains can be preferentially parallel or        perpendicular to the surface. Surface energy effects can cause        orientation of polymer chain side groups either outward from the        surface or inward towards the bulk of the film formed from the        printed liquid, forming a variety of conformations.    -   (iii) The electronic surface region has dimensions that range        from about 0.1 nm (1 Angstrom) to 1 nm (10 Angstroms).        Mechanical and chemical properties of the surface may influence        the bulk material performance to a greater depth.    -   (iv) Inorganic crystalline lattice (3-D periodicity) surface        state formation defects are rarely observed on carefully        prepared polymer surfaces. Dangling and unsatisfied surface        bonds are rarely observed. For conjugated polymers, the covalent        bonds are satisfied, and the largely one-dimensional nature of        the polymer chains is preserved, despite the gentle curvature,        bending, and end chain termination occurring at or near the        surface.        Forming a Thin-Film Transistor

In one embodiment, the component formed by a printing apparatus 10 ofthe invention is an electrical component, such as a field effecttransistor, preferably having a multiple layer printed structure. Eachcomponent layer of the transistor can be formed from polymeric material.Deposition from a stream of droplets can be used for single or formultiple layers of the device, for example, for the organicsemiconductor and/or insulator. In one embodiment, an adapted continuousink jet print mechanism, with nozzles and supporting structures adaptedaccording to the present invention is used to fabricate the completedevice, including semiconductor layer, insulating layer, metalliccontacts, and encapsulation and protective coating layers. Preferably,the device is fabricated onto a flexible, moving support 14, usingsuccessive droplet deposition steps.

In order to fabricate a polymer transistor capable of controlling alight emitting element, droplet deposition of a component material froma continuous stream may be employed for forming one or more of a numberof key layers, such as the following:

-   -   (i) Gate Dielectric. Suitable materials the gate dielectric can        include BenzoCycloButane (BCB), polysiloxane, polyaniline, and        polymethyl methacrylate (PMMA), for example.    -   (ii) Semiconductor materials. Suitable materials include        pentacene and polythiophene, for example.    -   (iii) Light emissive polymers, including polyfluorene and        MEH-PPV        (poly[2-methoxy-5-(2′-ethyl-hexyloxy)]-p-phenylene-vinylene),        for example.    -   (iv) Protective Sealant. Suitable materials for protective        sealant can include multifunctional UV curing acrylates and        organically modified ceramics (such as organosilane derivative),        for example.    -   (v) Polymeric Conductors. Suitable materials for the polymer        conductor can include polyaniline (for example, blended with        polyethylene or other suitable substance) and polythiophene, for        example.

Referring to FIGS. 6A and 6B, there are shown cross-sections of a fieldeffect transistor 90 formed on a support 92. Transistor 90 comprises agate region 94 formed from doped polyaniline or from Cu[hfacac]; a gateregion insulator spacer 96 formed from polyimide, PMMA or siloxane; agate insulator 98 formed, depending on the gate characteristics, frompolyimide or siloxane; a source region 100 formed from doped polyanilineor Cu[hfacac]; a drain region 102 also formed from doped polyaniline orCu[hfacac]; and an active semiconductor region 104 formed frompentacene, preferably doped pentacene. An acrylate-doped ormocer ormethoxysilane-based protective layer 106 can be formed over the surfaceof transistor 90 for hermetic isolation of transistor 90.

Gate region insulator spacers 96 are shaped for control of the electricfield gradient at the edges of gate region 94 in order to minimizeleakage current. Spacers 96 can have any desired shape, within thelimits set by droplet size and curing technique used.

As an example, a fabrication method using selective droplet depositionfrom a continuous stream of droplets may comprise the following steps:

-   -   (1) depositing gate region 94 on support 92;    -   (2) depositing gate insulator layer 98 over gate region 94;    -   (3) depositing source region 100 and drain region 102 on gate        insulator layer 98, where source region 100 is separated from        drain region 102; and    -   (4) depositing active semiconductor layer 104 between source        region 100 and drain region 102.

This method may further comprise, prior to depositing gate insulatorlayer 98, the step of depositing a gate electrode insulator layer ateach end of gate region 94. This may further comprise, prior todepositing active semiconductor region 104, the steps of depositinginterface layers on facing walls of drain and source regions 102 and 100into which the active semiconductor material diffuses, during depositionor curing, to control the barrier height of transistor 90. The methodmay further comprise the step of depositing an organically modifiedceramic layer over transistor 90 for hermetic isolation of transistor90.

Polymeric transistor 90 can be deposited directly onto a wide variety ofsupport 92 including flexible supports. The list of possible supportsincludes, for example, thin film single crystal, polycrystalline, oramorphous surfaces, single bulk crystals, glass, plastic, metalincluding metallic alloys, treated or untreated paper or card, or anytemperature sensitive material including low glass transitiontemperature plastics, or a range of or synthetic or artificialsubstitutes. This support 92 can be provided in a continuous form or fedas individual sheets.

Referring to FIG. 6B, in order to control the barrier height, aninterface layer 108 is formed on the facing walls of source region 100and drain region 102 prior to the deposition of active semiconductorregion 104, and into which active semiconductor region 104 diffusesduring deposition and/or curing processes. Interface layer 108 may beformed from TCNQ or a liquid equivalent.

A range of liquid material and diluent carrier or dopant properties canbe used in manufacture of a practical device or element. For the sake ofillustration, and not by way of limitation, particularly suitable fluidproperties and ranges could include the following:

-   -   Ambient pressure=1.01×10⁵ to 1×10⁻⁶ N m⁻²;    -   Boiling point=0 to 250 degrees C.;    -   Droplet velocity=0.1 to 20 m s⁻¹;    -   Dynamic viscosity=1 to 200 mPa s;    -   Heat of vaporization=Liquid dependent J mol⁻¹;    -   Liquid density=Liquid dependent, in kg m⁻³;    -   Material density=Material dependent, in kg m⁻³;    -   Material solid content=0.0001 to 100%;    -   Static contact angle to the support=0 to 90 degrees;    -   Support temperature=270 to 600 K;    -   Surface tension=20 to 76 mN m⁻¹; and    -   Temperature coefficient of viscosity=Liquid dependent, mPa s K⁻¹

Both device structure and droplet properties can be tuned to optimizedevice performance and behavior. Tunable parameters could include thefollowing:

-   -   Electrode geometry and thickness;    -   Insulating layer geometry;    -   Liquid droplet dynamic wetting rate and contact angle;    -   Liquid droplet rheology;    -   Liquid droplet static contact angle; and    -   Support fluid capillarity (wicking under existing layers).

Printhead operational reliability and stability depend on parametersincluding liquid material properties, nozzle geometry and manufacturingprocesses and materials used for the droplet deposition mechanism. Forthe potential manufacture of an all-transparent transistor 90, suitablyprepared polyaniline can be substituted for the conventional ITO (IndiumTin Oxide) as a transparent electrode. Polyaniline has surfaceconduction and hole injection performance characteristics comparable toITO.

Transistor 90 can be a back-to-back diode pair, or may be a field effectenhancement or depletion mode transistor. The capability to formtransistor 90 onto a flexible support shows the overall capability ofthe method of the present invention for fabricating a broader range ofelectronic and optical devices, including devices employing p-njunctions such as various types of photodiodes, diacs, triacs,thyristors, bipolar devices, field-effect devices, phototransistors,lasers, photodetectors, electronically stimulated light sources,superconducting computers, and very high speed UV, visible, IRopto-electronic switches (PPV and associated derivatives). These devicesmay provide AC, DC, pulsed, low voltage, or fast switching operation.Selective droplet deposition from a continuous stream of droplets canalso be used in the manufacture of inorganic semiconductor devices basedon materials such sol-gel ITO, Sn chloride, and other aqueous solutions.For example, the droplets used to form respective layers or regions canbe supplied by a series of continuous ink jet droplet depositionprintheads adapted as was shown in FIG. 5A. Alternatively, the dropletsforming respective layers or regions can be supplied by selectivedroplet deposition from a continuous stream of droplets provided from aplurality of separate fluid supplies.

Transistor 90 may be a buckminster fullerene and fulleride C₆₀-basedtransistor. The term “C₆₀-based” includes other structures of fullereneand fulleride molecules, including, but not limited to, C₇₀, C₇₆, C₇₈,C₈₂, C₈₄ and C₆₀-TDAE (tetrakis-dimethylaminoethylene). These types oftransistors have generally higher mobilities and temperature stabilitythan do conventional polymer transistors.

Depositing Conductive, Semiconductive, and Dielectric Patterns

Broadly stated, the present invention provides a method of forming anyof a number of types of patterned circuit element(s) on a surface usingselective droplet deposition from a continuous stream of droplets. Typesof circuit element formed could include any component of an electriccircuit having an arrangement of layered insulating, resistivedielectric, or conducting materials, including conductive traces betweencomponents. The circuit element may be formed from organic, inorganic,or hybrid inorganic-organic materials. Optical components and coatingscould also be applied using this method. This can be used for example asgenerally described above for the purposes of forming, a component of anelectroluminescent element, light emitting diode, an organic lightemitting diode, polymeric light emitting diode a transistor, aconductor, a resistor, a diode, an optical circuit, an electricalcircuit, a fluidic circuit, an opto-electronic device, or anelectromechanical device.

The present invention allows features such as patterned circuit elementsto be formed using a process that requires fluid deposition only,without photolithographic masking. Using continuous flow dropletdeposition, component materials can be deposited only where required,without the need to remove deposited material such as by etching. Thisenables fabrication of a range of components such as flexible printedcircuits, with conductive traces extending between circuit elements.This technique can be effectively used for web-based fabrication, sincemultiple passes of the same printhead would not be required withcontinuous flow ink jet printing.

A patterned circuit element formed using printing apparatus 10 (FIGS.2A, 2B) may be electrically conductive and may additionally includesemiconductor or dielectric materials, and can be opaque, absorptive,reflective, or transparent. Optically transparent conductors exhibitingbetter than 10 Ohms per square resistivity, of considerable interest tothe electronics industry in general, are of particular value inmanufacture of electro-optic devices such as displays. ITO[indium-tin-oxide], for example, is one very widely employed transparentconductor, advantaged for opto-electronic devices due to its relativelylow plasma frequency and transparency to visible light, and is widelyused for traces and bus line features. However, ITO can be difficult topattern. ITO has a work function of 4.7+−0.2 eV, depending upon themorphology and purity of the coating and the deposition method.Alternately, polyaniline has similar work function and surfaceconduction properties.

A conductor could also be a metallic material, such as might beadvantaged for use as the source and drain of a field effect transistor.A suitable metallic conductor may be formed from organometallic ormetallo-organic compounds, such as those used for the deposition ofcopper, for example:

Cu[COD]hfacac—(hexafluoroacetylacetonate)Cu(1,5cyclooctadiene); and

Cu[TMVS]hfacac—(hexafluoroacetylacetonate)Cu(vinyltrimethylsilane).Other metals, for example, Au, In and Sn, may be included in suchcompounds. Other suitable conductive deposition materials include ITOsol-gel, metal colloids and inks, organically modified ceramics, andorganically modified silicate, for example. As is emphasized in thebackground section given above, selective droplet deposition from acontinuous stream of droplets is generally advantaged over alternativedroplet placement methods for depositing colloidal materials. In anotherembodiment, polymeric conductors can be used. Conductive polymersinclude, but are not limited to: polyaniline (which may be highlystretched), polyacetylene (including iodine doped and stretch ordered),polythiophene (including stereoregular), polypyrrole and polysilanecompounds (including modular silylenes), stearic acid, substitutedpthalocyanines, indoles, and furans.

Typical conjugated polymers include, but are not limited to thefollowing: trans-polyacetylene, PA, poly(para-phenylenevinylene), PPV,and poly(para-phenylene), PPP, polyaniline, polyacetylene,polythiophene, polypyrrole compounds, polysilane compounds, stearicacid, substituted pthalocyanines, indoles, furans, cis- andtrans-polyacetylene, polyparaphenylene, polydiacetylenes,polybithiophenes, polyisothianapthene, polyphenylenesulfide,polythienylvinylenes, polyphenylenevinylenes, EDOT(3,4-ethylenedioxythiophene), and PEDOT (polyethylenethioxythiophene).Alternately, other opaque materials such as carbon black could be used.

The patterned circuit element may comprise a plurality of stackedelectrically conductive elements connected by via holes for electricalcontact between layers. A circuit element may have one or more isolationlayers disposed between adjacent elements. Such an isolation layer canprevent electric field interactions or interference between adjacentpowered electrodes.

Electrical contacts or electrodes can be deposited to provide connectionto an electrical, electronic, or opto-electronic device. The contactarea geometry and materials employed determine the overall quality ofthe electrical contact. Selective droplet deposition from a continuousstream of droplets can also be used to form a pre-patterned conductivestructure onto a support. For example, variably spaced contacts can bedeposited onto a piezoelectric ceramic, onto a thick film, or onto athin film element. A continuous ink jet printing mechanism adaptedaccording to the present invention provides a means of depositingconductive element patterns without the need to use whole-area thin orthick film deposition methods in conjunction with photolithographicpatterning and wet or dry etching techniques.

In yet another aspect, the present invention provides a method offorming conductive patterns by conditioning the electrical conductivityof a material. For example, this method can be used to enhanceconductivity of at least part of a partially cured insulating layerusing electrostatically focused electrically conductive particlesdeposited using continuous ink jet printing. Selective dropletdeposition from a continuous stream of droplets can be used toselectively introduce a liquid to a surface to induce electronic statechanges at, or close to, the point of printing in order to effect acontrolled change in characteristics of the material to be treated. Suchcontrolled doping or loading of a surface or sub-surface regionintroduces mobile charges that can affect the current carryingcharacteristics of a component material with a majority (or minority)carrier impurity. The doping can introduce local material propertychanges as a result of the mode of doping, including chemical, protonic,electrochemical, optical, and electronic changes.

In another embodiment, a continuous ink jet print head adapted accordingto the present invention can be used to deposit a precursor material forconditioning the characteristics of one or more other depositedmaterials. For example, a precursor material could be deposited in apattern, followed by the deposit, coating or application of a secondmaterial, thereby forming a patterned conductor due to the reaction ofthe precursor with the second material. Application of heat, light, orother form of energy can be used to initiate or enhance the reaction ofthe precursor with the second material. For example, the precursormaterial could be exposed to a chemical bath resulting in a functionalpattern. A specific example of this could be a pallidium catalystprecursor pattern that is contacted with an electroless platingsolution. The use of precursor materials is well known to those skilledin the device fabrication art.

In one alternative method, a polymerization catalyst is first depositedonto a substrate, in a pattern. Suitable polymerization catalysts forthe polymerizable compound may include, for example, metal salts such asferric chloride, cupric chloride and cupric sulfate; metal oxides suchas lead dioxide; peroxo acid salts such as potassium persulfate andammonium persulfate; quinones such as benzoquinone; diazonium salts suchas benzenediazonium chloride; potassium ferricyanide;hexachloroplatinate (IV); and the like. Next, a monomer or oligomer isdeposited from an ink jet print head, in a layer overlaying the catalystpattern. Examples of the polymers which can be formed in this mannerinclude, for instance, organic synthetic polymer such as polyvinylacetal, polycarbonate, polyvinyl butyral, polyacrylate,polymethacrylate, polymethyl methacrylate, polyethylene, polypropylene,polystyrene, polyacrilonitrile, polyvinyl acetate, polyvinyl chloride,polyvinilidene chloride, polyvinyl fluoride, polyvinylidene fluoride,polyvinylidene cyanide, polybutadiene, polyisoprene, polyether,polyester, polyamide, polyimide, silicone, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide and polyethylene glycol; derivativesthereof; and the like. The polymers include copolymers such asstyrene-acrylate copolymer, vinyl acetate-acrylate copolymer andethylene-vinyl acetate copolymer. Also included are natural polymerssuch as cellulose, starch, casein and natural rubber; semisynthetic highmolecular compounds such as cellulose derivatives, for example methylcellulose, hydroxyethyl cellulose and carboxymethyl cellulose; andinorganic polymers such as glass, silica and alumina. The catalystconditions the overlaying polymer compound to form an electricallyconductive polymer pattern conforming to the deposition pattern of theoriginal catalyst.

Where a conventional continuous ink jet print head uses electrostaticcharge for droplet deflection, conductive particles may be introduced toassist directional steering of droplets towards a selected region of acomponent. This method can be applied to forming an entire electricallyconducting element, such as an electrode or trace, or to the treatmentof a specific location, such as a contact region where conductiveparticles improve local conduction to provide a region having a lowercontact resistance and which can be used as a bonding platform. The rateof diffusion of conductive particles into the layer may be determined bythe type or intensity of radiation used to fix or fully cure the layer.

Forming metal and/or inorganic transparent patterned conductors involvesdepositing a precursor material onto a moving web using selectivedroplet deposition from a continuous stream of droplets and subsequentthermal processing to produce the final conductor material. Conversionprocesses include Metal-Organic Decomposition (MOD) in which ametallo-organic molecular material is dissolved in a solvent and couldinclude optional film-forming additives. With MOD, for noble-metals, thedeposited precursor films can be pyrolyzed in air to produce the metalfilms. For non-noble metals, thermal decomposition can be performed inan inert or a reducing environment. The MOD approach can also be appliedto transparent conducting oxides, although relatively high processingtemperatures require compatible support materials. Certainly, metals,oxides, and various glass types are candidate web materials for theseprocesses.

An alternative approach is to use metal nano-particle precursors whosevery high metal surface areas afford large melting point depression andallow continuous metal films to form from the precursors at very lowtemperatures. This nano-particle precursor approach is particularlycompatible with plastic film webs. Noble metal nano-particle precursorsare particularly suitable as materials to be deposited using selectivedroplet deposition from a continuous stream of droplets for the purposesof producing patterned layers on a moving support, such as is used inweb-based fabrication.

Additional processing steps may be required to treat some or allportions of conductive patterns deposited using the droplet depositionmethod described above. For example, curing treatments, exposure toradiation of selected wavelengths, annealing, or other methods could beused to condition the conductive material.

As noted above, selective droplet deposition from a continuous stream ofdroplets can be used for materials that are conductors as well asmaterials that act as semiconductors and dielectrics. The followinglisting gives an approximate range of resistivity for classifying thesematerials:

-   -   (i) Conductors have resistivity values ranging from about 10⁻⁴        to 10⁻⁶ ohm-cm;    -   (ii) Semiconductors have resistivity values ranging from about        10⁻³ to 10¹² ohm-cm;    -   (iii) Dielectrics have resistivity values ranging from about        10¹⁰ to 10¹⁸ ohm-cm.        Typical dielectrics of interest include Hydrogensilsesquioxanes,        fluorinated benzoxale, Teflon AF, and nanoporous silica.        Depositing a Patterning Mask

A conductive pattern, or other suitable pattern of material that is aconductor, a semiconductor, or a dielectric, can also be formed using aprocedure that combines the steps of depositing a coating havingconductive or insulating characteristics, depositing a patterning maskover a portion of the coated area, and processing the masked area toform the pattern. The patterning mask can be made from materials thatinclude, at least in part, photosensitive, radiation sensitive, solventsensitive, or heat sensitive. The patterning mask may be photosensitive,radiation sensitive or solvent sensitive. Referring to FIG. 7, there isshown, in perspective view, a portion of a patterning mask 70 used toform a pattern in a conductive coating 72 applied to support 14. Coating72 may be applied using selective droplet deposition from a continuousstream of droplets or by some other suitable coating method, includingoffset or screen printing, for example. Patterning mask 70 is thenapplied on coating 72; two portions 74 of patterning mask 70 arerepresented in FIG. 8. Subsequent processing is then used to removemasked or unmasked portions of coating 72, forming the pattern thereby.Processing for this purpose may use wet or dry chemical processing,photo-processing, or other known etching techniques. Patterning mask 70may include an oxidant or other substance for conditioning theconductivity or other properties of the underlying material.

Coating 72 can comprise at least in part, one of a polyaniline,polythiophene, organically modified ceramic, organically modifiedsilicate, sol-gel, carbon black, polyaniline compounds, polyacetylenecompounds, polythiophene compounds, polypyrrole compounds, polysilanecompounds, stearic acid, substituted phthalocyanines, indoles, furans,polyparaphenylenevinylene, polyparaphenylene, polydiacetylenes,polybithiophenes, polyisothianapthene, polyphenylenesulfide,polythienylvinylenes, EDOT, PEDOT, fluids containing particles, metals,semiconductors, conductors, insulators, and glass.

In certain embodiments, one advantage of the masking arrangement shownin FIG. 7 relates to the ability to vary the thickness of coating 72when using selective droplet deposition from a continuous stream ofdroplets. Unlike conventional masked pattern formation, in which thethickness of coating 72 is necessarily fairly uniform, the method of thepresent invention allows areas of variable thickness, such as isrepresented by depression 76 in FIG. 8. This capability for variablecoating 72 thickness enables formation of a conductive pattern of traceshaving varying thickness, for example, which can be advantageous forproviding fusible links or contact electrodes. The use of selectivedroplet deposition from a continuous stream of droplets for applying acoating layer is particularly advantageous due to the precision controlof droplet size available using this method, whether a uniform ornon-uniform coating thickness is needed.

A continuous flow ink jet print head, adapted according to the presentinvention, could be deployed as an alternative deposition device inapplications where spray bars are currently used, such as forapplication of uniform coatings, for example. Advantaged due to size andprecision, an adapted continuous flow ink jet print head allowsprecision placement of coating material, without masking, and allowscoating application immediately prior to deposition of other materials.

Nanoscale masking, wherein a masked feature is less than 1 micrometer inone or more in x-axis, y-axis dimensions, is also possible. This impliesa feature of size less than or equal to 999 nm. In order to achieve sucha feature, it is necessary to consider solution type, surface wetting,and liquid drop surface tension effects, and the potential for nozzleblocking. To alleviate limitations, it is possible to employ methodsthat promote droplet reduction in flight so that the droplet arriving atthe surface to be treated with the pattern is of smaller volume relativeto the feature size of interest and to introduce a method ofpre-treating the surface either before, during, or following dropletimpact, so as to limit surface spreading of the deposited masking fluid.The actual thickness of the nanoscale patterning mask feature depends,at least in part, on the concentration of solid in the printed drop andon the number of layers that are printed one on top of the other.

An example is a method of forming a nanoscale masking feature using asingle or multiple printed layer(s) whereby the following are applied:

-   -   (i) employ a printhead (single nozzle or nozzle array) that has        a nozzle size of preferably less than or equal to 10 microns        diameter; and    -   (ii) use a material that forms a highly homogeneous solution        that has been filtered to 0.1 microns and that is soluble in a        wide variety of solvents, preferably low boiling point solvents.        The solution can be a mixture of variable boiling point solvents        to facilitate easy jetting, elimination of nozzle drying, and        controlled in-flight evaporation.

The process of evaporation, volatilization, solidification or otherchange requiring energy transfer can be assisted by an in-situ lamp,laser, solid-state device, or semiconductor-based radiation source,depending upon the properties of the deposited material. The appliedelectromagnetic wave spectral bandwidths may span, for example, softX-ray, deep ultraviolet, ultraviolet, visible, infrared, or microwavefrequencies. Such a wavelength selectable radiation source can eitherprovide whole area exposure covering the pathway of the droplet from thenozzle to the support surface or could provide a steered, focused, orcollimated high intensity radiation source that can be used with asingle nozzle (matching nozzle density to laser output density, forexample). The radiation source could be a solid-state device, laser,LED, or other source.

Using a conventional approach, masking can be performed by applying amasking layer onto a coating, then performing some treatment thatconditions the uncoated and coated areas differently. Alternately,masking can also be effected by selectively treating areas of thecoating, without adding a separate masking layer. The treatment appliedcould use light energy or chemical application, for example.

Forming Integral Mask Layers

Patterned layers of many types, including metal or polymer layers, canbe formed using continuous patterned deposition of etch resists over oneor more unpatterned or pre-patterned layers. Alternately, one or more ofsuccessive patterned layers can be formed by depositing a continuousfilm over a patterned resist, such as a precursor to a lift-off process.Advantageously, mask layer materials for these and similar results canbe readily deposited onto a moving support using selective dropletdeposition from a continuous stream of droplets, without the need toincrease resolution by passing the support beneath the same print headmultiple times.

Useful Mask Materials

Continuous ink jet printing for providing selective droplet depositionfrom a continuous stream of droplets is flexible and low-cost comparedwith alternative technologies and enables integral patterned-maskformation on a high-speed web. Useful mask materials that can bedeposited using continuous ink jet print heads include polymer layersthat can be solvent cast or polymers deposited as liquids at elevatedtemperature.

Examples of water soluble polymers for this purpose are sodium andcalcium polyacrylic acid, polyacrylic acid, polymethacrylic acid,polymethylvinylether co-maleic anhydride, polyvinylpyrrolidone,polyethylene oxide, hydroxypropyl cellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, hydroxymethyl methacrylate, sodiumcarboxymethyl cellulose, calcium carboxymethyl cellulose, methylcellulose, maltodextrin, xanthan gum, tragacanth gum, agar, gellan gum,kayara gum, alginic acids, pectins, pre-gelatinized starch, andpolyvinyl alcohol, and blends of those polymers.

Some example non-aqueous soluble polymers and thermosetting polymersthat could be used for integral masking could include Cellulose acetate,Cellulose acetate butyrate, Polycarbonate, polyethylene, PMMA,Polystyrene, Polystyrene acrylonitrile, PVC, and ABS. Of these PMMA,Polystyrene, and Polystyrene acrylonitrile are preferred for solubilityreasons.

Composite Masking

Composite masking techniques can also be provided using selectivedroplet deposition from a continuous stream of droplets and acombination of additional techniques for selective curing. Referring toFIG. 8, there is shown a cross section view of two sections ofpatterning mask 70 and 70′ deposited on coating 72. Patterning mask 70and mask 70′ can be the same material, subjected to different treatmentin curing, so that patterning mask 70 and mask 70′ have differentcharacteristics. For example, laser light for curing can be directed topatterning mask 70′, but not to mask 70. Or, a curing material could beprinted onto patterning mask 70, but not onto mask 70′ in a subsequentprint operation, such as by a second print head. In this way, a varietyof composite masking arrangements are now possible using selectivedroplet deposition from a continuous stream of droplets.

With reference to FIG. 8, for example, the following composite maskingsequence could be performed:

-   -   (1) deposit coating 72 on support 14;    -   (2) deposit masks 70 and 70′ in one printing pass, of the same        material;    -   (3) treat mask 70′ using laser radiation, leaving mask 70        untreated;    -   (4) treat exposed areas of coating 72 in a first process;    -   (5) dissolve mask 70, leaving treated mask 70′ in place;    -   (6) treat exposed areas of coating 72 in a second process; and    -   (7) dissolve treated mask 70′.        Forming Relief Structures

Material deposition from a continuous stream of droplets may also beused for forming relief structures that contain or channel a fluid toprovide a patterned layer or patterned coating. Patterned coatings aregenerally useful for the fabrication of substantially planar devices,such as electronic displays, for example. In one embodiment, a reliefpattern is deposited using a first fluid and, optionally, one or moreadditional fluids. Droplets of a filler fluid, immiscible from fluidsused for the relief pattern, are then deposited to fill channels formedbetween the various relief structures.

Immiscible fluids may be chosen from water, polar organic liquids, andnon-polar organic liquids, or solutions using these liquids as solvents.For example, adjacent lines of non-polar organic liquid or solvent arefirst printed. Then, while still wet, the space between the adjacentlines is filled with an aqueous solution or water. Upon drying, thematerial (for example, the conducting polymer) in the aqueous solutionis deposited with lateral dimension defined by the spacing between theadjacent lines.

As another example embodiment, a channel can be formed by depositingadjacent lines of a material using selective droplet deposition from acontinuous stream of droplets. Once the adjacent lines dry, a fillerfluid material could then be deposited. In yet another embodiment, ahydrophobic material (such as carnauba wax, for example) could bedeposited onto a relatively hydrophilic support, using ink jet printing,for example. The patterned support can then be coated with an aqueoussolution that subsequently dewets from the hydrophobic pattern, creatinga pattern of wet and dry areas. This method of preparing heterogeneouscoatings or patterned coatings (also termed continuous discretecoatings) would benefit from a high-speed ink jet printing methodcapable of depositing a hydrophobic material.

Forming Display Devices

The present invention also relates to the application of selectivedroplet deposition from a continuous stream of droplets for formingelectro-luminescent and other types of display components, particularlyonto a moving support. Referring to FIG. 9A, there is shown, incross-section, a display pixel 110 formed on a rigid or flexible support112. A suitable flexible support is polyethylene-terephthalate (PET),for example. Pixel 110 has a base contact layer 114, which may bereflective, formed from aluminum or Cu[hfacac], for example. Upon basecontact layer 114 are deposited isolation insulators 116. Isolationinsulators 116 can be formed from polyimide, poly-methyl-methacrylate(PMMA) or siloxane. An active polymeric electro-luminescent region 118is shown and can be typically from a poly(p-phenylene-vinylene (PPV)derivative. A top contact 120 is typically formed from a transparentormocer or polyaniline. Base contact layer 114 may alternately be opaqueor absorptive or may act as a filter, reflecting, transmitting, orabsorbing light based on wavelength.

FIG. 9B is a cross-sectional view showing an alternate display pixel 110formed on an active switch shown as transistor 122 which is similar tothe transistor shown in FIGS. 6A and 6B. Transistor 122 is firstdeposited on support 112 to form the active matrix backplane. Displaypixel containment wells 117 are then printed adjacent to the switchingtransistor 122, the geometry of the containment optimizing the effect ofsurface wetting and planarized in-fill. An array of suitable drivingcircuits and electro-luminescent pixels 110 can be provided forformation of a red, green and blue pixel set, for example.

The present invention also relates to the manufacture and use of anarray of pixels 110 in the form of polymer light emitting diodes (PLED).Such a polymer LED array can be manufactured using some combination ofevaporation, sputtering, spin-coating, L-B, and droplet depositionmethods. The polymer electro-luminescent material used can be selectedand tuned for a specific wavelength range. Suitable materials include,but are not limited to, PPV and MEH-PPV[poly(2-methoxy,5-(2-ethylhexoxy)-1,4-phenylene-vinylene)]. The polymerLED can be manufactured adjacent to the nozzle array with at least asingle emissive pixel 110 at a time, each pixel 110 associated with eachprint head nozzle.

Selective droplet deposition from a continuous stream of droplets can beused to print either or both the active matrix switching array, ordisplay pixel 110, transistor 122 or an active matrix comprising anarray of electrical leads, pixels 100 and transistors 122. Of keyimportance is the electronic state of the printed interfaces between theactive elements of the transistor or the display pixel. Typically, anarray of switching transistors 122 is first formed on a flexible supportto form an active matrix backplane. Display pixel containment wells arethen printed adjacent to the switching transistors (with one set oftransistor and charging capacitors per color pixel set). The containmentwell geometry is designed to optimize surface wetting and planarizedin-fill.

It will be appreciated that other types of drive electronics can beformed using such techniques. For example, a direct drive scheme can beformed in like fashion. Direct drive systems are well known in the artfor use in addressing segments of a segmented display such as a liquidcrystal display of the type found in wrist watches, calculators and thelike. With direct drive addressing each segment in the display has itsown drive circuit. To turn an individual segment on or off a voltagemust be applied to an electrical lead attached to the segment. A commonelectrical lead is connected to all segments in order to complete acircuit across the segment.

Light emitting polymer pixel 110 can be formed using containing walls tolimit the inter-penetrability of the different fluid types required todeposit the transistor and the light emitting pixel or the differentemission colors of a full color display. The width of such wellstructures falls within the Rayleigh criterion for the viewing distanceof the screen. Rayleigh's criterion suggests that the observed patternsbe considered distinguishable when the first minimum of one falls on thecentral maximum of the other (or better). When the pupil is small theresolving power of the eye is about 10⁻⁴ radians of arc. This controlsthe minimum separation of points that are to be distinguishable: the eyecan “just resolve” points 0.1 mm (100 microns) apart when they are 250mm from the eye. This would reduce to about 40 microns at a viewingdistance of 100 mm. The material is of such a nature as to be opaque toUV and visible light.

Typical polymer displays include, but are not limited to, light emittingamorphous and small molecule polymers, ferroelectric polymers, electrochromic polymers, photo chromic polymers, electrorheologic polymers,electroactive polymers, electro-optic polymers, opto-electronicpolymers, and liquid crystal polymers.

For polyaniline (or polyaniline+up to 70 wt % TiO₂ particles of size at20 nm), multiple color changes occur at different electrode potentialsin the range −0.2 to −1.0 volts (taken with respect to a standardcalomel electrode), with color varying from yellow, through green, todark blue. Polyaniline is usually operated at below the second oxidationpotential, thus providing one color change from pale yellow to green.This means that for full color displays, the polyaniline material needsto be combined with another material such as tungsten oxide or Prussianblue. Photo reduction-based electrochromism is also a possible operatingmechanism.

Preferably, the display device has a plurality of portions comprisingrespective layers of a multi-layer display device. Preferably, thedisplay comprises at least one electrically active display pixel, atleast two adjoining portions of each pixel being formed from one or moredifferent deposition materials. Printed materials could include, butwould not be restricted to, conjugated polymers (for example, MEH poly(phenylene vinylene); polythiophene; and polyacetyllene derivative.

The display element can be based on a pale yellow color (which can beprovided by the deposition of polyaniline) as the neutral transmissioncolor, which color changes to provide the necessary contrast forinformation transfer to the eye. For polyaniline, multiple color changesoccur at different electrode potentials in the range −0.2 to −1.0 volts(taken with respect to a standard calomel electrode). The color variesfrom yellow, through green to dark blue. Polyaniline is usually operatedat somewhat below the second oxidation potential, thus providing onecolor change from pale yellow to green.

Solution processed OLED materials that can be provided as a fluid forselective droplet deposition from a continuous stream of dropletsinclude soluble small molecules, oligomeric and polymeric materials. Thematerials can either be dissolved or dispersed in appropriate solvents.Typical oligomeric and polymeric materials include, for example, arenesand arene vinylene derivatives. Suitable polymeric materials includelinear polymers, ladder and step ladder polymers, star polymers andhyper-branched polymers. Oligomeric materials also include dendrimers.For example, typical polymers are poly (p-phenylenevinylene) (PPV)derivatives, poly(p-phenylene) (PPP) derivatives, polyfluorene (PF)derivatives, poly(p-pyridine), poly(p-pyridalvinylene) derivatives,polythiophene derivatives, poly(thionene vinylene) derivatives, andpolycarbazole derivatives. Typical oligomeric materials includeoligo-PPV, oligo-PPP, oligo-PF, oligo-carbazole, and oligo-thiophene.Solution processed OLED materials can be a combination of more than onematerial. These materials can also be used in combination with one ormore than one dopant.

Selective droplet deposition from a continuous stream of droplets canalso be used for various stages in preparation of other types ofdisplays and supporting films. For example, color filter arrays (CFAs)and other film structures can be fabricated using droplet deposition ofsuitable materials.

Barrier Coatings

It is a known problem that the penetration of oxygen and water into thinfilm display devices or other structures can severely degrade devicelifetime. Unprotected, for example, a newly fabricated OLED device wouldlast only minutes before its destruction by oxygen and by airbornemoisture. LCDs must also be protected to prevent the formation of gasbubbles that degrade their performance. One method for preventingpenetration by oxygen and moisture is to fabricate a sandwich structureusing glass and glued metal on the outside, with the protected OLED orLCD material on the inside. However, such devices tend to be bulky,rigid, and costly and, in consequence, are incompatible withmanufacturing goals for low cost display devices on flexible supports.Recent developments in barrier coatings suitable for flexible displayinclude the use of a stacked structure of resin or polymer and ceramiclayers. However, the manufacturing process for such composite structurescan require a number of repeated stages, with multiple entry and reentryinto vacuum deposition chambers in a process that is time consuming andcostly.

Referring to the side view of FIG. 10, there is shown an OLED 80 havingthis type of barrier coating applied using selective droplet depositionfrom a continuous stream of droplets. An active OLED layer 82 isdeposited on support 14 and is protected by a sandwiched arrangement ofalternating polymer isolation layers 86 and ceramic layers 84, printedusing a continuous ink jet print head. Examples of suitable polymermaterials that can be deposited could include, but are not limited to,acrylate monomer, carbonate monomer, ester monomer, or urethane monomerwhich may be cured by application of heat or UV radiation or radiationof some other wavelength. Similarly polyacrylates, polycarbonates,polyurethanes, or polyester may be deposited, then cured by heat, UVradiation, or radiation of other wavelength with or without across-linking agent. Preferably, these materials would be transparent.Examples of ceramic materials that can be deposited would include, butnot be limited to, liquid preparations containing Silicon oxide,titanium oxide, silicates, titanates, organic modified sol-gelprecursor, sol-gel precursor, aluminum oxide, and other glass formingmaterials. Preferably, these materials would also be transparent.

Alternatively, printing droplets, non-printing droplets and/or satellitedroplets can be cured before such droplets strike support 14, a gutter,and/or catching mechanism. Such curing can be achieved, for example, byexposing the droplets to a gas, heat, or energy before the dropletsstrike the support, gutter, and/or catching mechanism. It will beappreciated that where gas pressure is applied to deflect the droplets,the gas used to supply such pressure can be selected to perform thecuring.

Deposition Materials and Supports

Suitable deposition materials for electronic device fabrication usingselective droplet deposition from a continuous stream of dropletsinclude, but are not limited to, the following:

-   -   (a) Conductive Polymers: polyaniline, polyacetylene,        polythiophene, polypyrrole, indoles, furans, substituted        phthalocyanines, stearic acid, trans-polyacetylene, PA,        poly(para-phenylenevinylene), PPV, and poly(para-phenylene),        PPP, etc.;    -   (b) Electrolytes and Electrolyte Separator: LiBF₄,        poly(2-acrylamido-2-methylpropanesulfonic acid), etc.;    -   (c) Fluorescent Materials: Fluorescent dyed polyesters,        fluorescent dyed polyethers, phosphors, ZnS:Ag, ZnS:Cu, Al,        Y2O2S:Eu, Y2O3:Eu, ZnO:Zn, ZnGa2O4, SrGa2S4:Eu, SrGa2S4:Ce,        Y3Al5O12:Tb, Y2Si5:Tb, YVO4, etc.;    -   (d) Insulators: ButylCycloButadiene (BCB), PMMA, polyamide,        polyimide, polysilane, spin-on-glass, methylsilsesquioxide        polymer, etc.;    -   (e) Metallic Colloids: Au, Pt, Ni, Cu, In, Sn, etc.;    -   (f) Metallic Pastes: Ag-dag, Au-dag, C-dag, particulate or        chemically doped polymeric systems, cermets (polyimide-Cu,        etc.), MOCVD-based particles, milled ceramics, milled crystals,        milled thin films, heterogeneous gas phase generated particles,        liquid-based particles etc.;    -   (g) Miscellaneous: Acid, alkali, fluorocarbon, H₂O, H₂O₂, HCl,        Hydrocarbon, Iodine, Oxygen, Quinone, Solvents, stable        orthorhombic phase crystal structure of the organic compound        p-nitrophenyl nitronyl nitroxide (p-NPNN), Oligomers, Nitronyl        nitroxides, Phenoxyl radicals, HNN (2-hydro NN), Biradical:m-BNN        (m-Phenylenebis[nitronyl nitroxide]), foams, hybridised        organic-inorganic system, phospholipids (including those        containing a mol % of cholesterol), arachidic acid monolayer,        etc.;    -   (h) Non-Wetting: Perfluorocarbons, etc.;    -   (i) Organo-metallics and Metallo-organics: Cu, Sn, In,        hybridised organo-metallics and metallo-organics (Cu dispersed        in an insulating matrix, etc.), tungsten oxide, nickel oxide,        etc.;    -   (j) Organically-modified Ceramics (Ormocers) including Ormosils,        siloxanes, silanes (TEOS—tetraethoxysilane);    -   (k) Polysilane compounds including modular silylenes;    -   (l) Protective Coatings: multifunctional acrylate, PMMA,        Ormocers, silane compounds [TCS, BTCSE, TMCS, etc.] etc.;    -   (m) Semiconductors and light emitters: pentacenes, polyanilines,        polythiophenes, polyacetylenes [including Durham pre-cursor        route], PPV derivatives, (i.e., MEH-PPV:        poly[2-methoxy-5-{2′-ethyl-hexyloxy}-1,4-phenylene vinylene,        [soluble in common organic solvents such as tetrahydrofuran        [THF], chloroform, dichloromethane, etc.]), MEH-PPV blend,        poly(arylenevinylenes), poly(3-alkylthiophenes), CN-PPV, PPV,        PT, PPP, poly(phenylenes), poly(quinoxalines),        poly(phenyleneacetylenes), fullerene and fulleride molecules,        including but not limited to, C₇₀, C₇₆, C₇₈, C₈₂, C₈₄, and        C₆₀-TDAE (tetrakis-dimethylamino ethylene), polyfluorene        crystalline polymer, etc.;    -   (n) Sol-gel Compounds: SnO_(x), ITO, PT, PZT, PLZT, tungsten        oxide, WO₃, TiO₂, ZnO, SnO₂, NiO_(x), MnO₂, Prussian blue, etc.;        and    -   (o) Polymer composites, including polymer materials supplemented        with additive filler materials.

Materials deposited may be conductors, semiconductors, or dielectricsubstances, for example, or various materials used to form opticalwaveguides and other optical components including but not limited toprisms, light focusing structures, optical conductors, lenses, lightblocking materials, and reflective structures.

Surface Preparation

Various additional processes could be employed for supporting selectivedroplet deposition from a continuous stream of droplets, includingprocesses that pre-condition the support surface. This can includedepositing a “subbing” layer onto the support, using droplet depositionor some other method. Subbing layer methods can include gravure,curtain, bead, slide, microgravure, and vacuum treatments.

A number of alternative methods could be employed for pre-treating thesurface. Available methods include, but are not limited to, coronadischarge, electrical charge application, magnetization, or chemicalpre-treating. More elaborate surface preparation methods could includeplasma discharge treatment, as is described in InternationalApplications WO 00/65887 entitled “Method And Apparatuses For PlasmaTreatment” by Bardos et al., and WO 00/63943 entitled “Large-AreaAtmospheric-Pressure Plasma Jet” by Selwyn et al. Yet other surfacemodification methods include saponification baths, dielectric barrierdischarge, flame treatment, and UV-ozone treatment, for example. Surfacepreconditioning can also include any number of cleaning treatments,using methods such as particle transfer rolls or cleaning baths. Onecomprehensive reference for surface treatments that may be suitable isModern Coating and Drying Technology, edited by Edward D. Cohen andEdgar B. Gutoff, John Wiley & Sons, 1992.

Types of Droplet Deposition Apparatus Used

The apparatus and methods of the present invention may employ any of anumber of types of mechanisms for selective droplet deposition from acontinuous stream of droplets, including continuous flow ink jet printheads of either the electrostatic-deflection type (as disclosed in theHertz '387 patent cited hereinabove), the micro-valve deflection type(as disclosed in the Lebens et al. '440 patent cited hereinabove) or thegas-flow deflection type. (as disclosed in the Hawkins et al. '197patent cited hereinabove). As has been observed, theelectrostatic-deflection type is suitable only where the deposited fluidhas some conductivity; insulators must be treated in some way in orderto allow their use with this type of continuous flow ink jet print head.The gas-flow deflection print head of the Hawkins '197 patent isparticularly advantaged for high-speed web fabrication, handling fluidshaving any level of conductivity and allowing increased distance fromthe surface of the receiving support and a droplet frequency that issignificantly higher than is available using other droplet depositionmethods. The micro-valve deflection type print head would also beadvantaged over the electrostatic deflection type for depositingnon-conductive fluids.

For forming features onto a surface using selective droplet depositionfrom a continuous stream of droplets, it has been found that, unlikeother droplet deposition methods which are hampered by poor resolutionand low volume delivery, the height to width ratio of a feature formedin a single pass can be greater than 0.25. Single-pass feature formationis advantaged because it minimizes cross-sectional striations in thelaydown material and, therefore, allows a more uniform density than doesmultiple-pass printing.

A high laydown density becomes possible with the use of the dropletdeposition apparatus according to the present invention. Laydowndensities in excess of 5 mg per square foot can be achieved.Furthermore, with the application of continuous ink jet technology, RMSdeviation for height and width of features formed on support 14 can bemaintained to within 1%. These measurable performance characteristicsclearly distinguish selective droplet deposition from a continuousstream of droplets from other types of droplet deposition technologiesconventionally used for flexible supports.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention as described above, and as noted in the appended claims, by aperson of ordinary skill in the art without departing from the scope ofthe invention. For example, the method and apparatus of the presentinvention flexibly allow a wide possible range of nozzle diameters andgeometries for forming and directing a stream of sequential droplets.Various treatment methods can be used to supplement the materialsdeposition methods of the present invention. Additional cleaning oretching steps can be used to remove or dissolve unwanted satellitedroplets 48 that have been deposited, as is shown in FIG. 11. Forexample, satellite drops 48 can be removed using laser ablation,washing, washing with a solvent and/or detergent, blowing with apressurized gas or liquid, or applying a surface energy treatment priorto printing to reduce the adhesion of the satellite drop to the surface.

Selected embodiments of method and apparatus of the present inventionadvantageously form electronic circuit elements and optical componentsonto a moving support at higher throughput speeds than areconventionally available using the drop-on-demand print heads currentlycommercialized for component manufacture. Using an apparatus equippedwith a continuous flow print head that provides selective dropletdeposition from a continuous stream of droplets, the distance betweenthe print head and the support can be increased over the tightlyconstrained distances permitted with the earlier drop-on-demandtechnology. Because additional space is available between the outlet ofeach print head apparatus and the support surface, a continuous flow inkjet print head can be more readily adapted for use with preconditioningcomponents that may be deployed for treating the support surface or forconditioning ink jet droplets that are directed toward the surface forforming the circuit pattern. For example, heat, solvent vapor,conditioning vapor, light, or ultrasound energy could be applied to adroplet in trajectory from the nozzle to the surface, as well as justbefore droplet emission or following droplet deposition. Whilecontinuous flow ink jet print heads that are adapted according to thepresent invention provide a mechanism that is suitable for use with manytypes of fluids and environments, alternate types of mechanisms could beused for selecting and directing printing droplets from a continuousstream of droplets. Alternative mechanisms could use electrical,mechanical, acoustic, piezoelectric, or other transducers for generatinga droplet stream, for example. Transport system 24 shown in FIGS. 2A,2B, and 2C moves support 14 past stationary printheads 12, 13, 13 a, 13b, and 13 c. However, formation of features on support 14 couldalternately be accomplished by moving one or more printheads 12, 13, 13a, 13 b, and 13 c relative to support 14. FIGS. 11-15 show top views ofan article 130 of the invention and illustrate articles that can beformed in accordance with the invention. As shown in FIG. 11 an article130 is provided having a single printed drop 56 on a support 132 ofarticle 130. Printed drop 56 has a printed diameter of between 10 and250 microns and has a radius R. As is shown in FIG. 11, not more thanone satellite drop 48 is positioned within a radius of three times theradius R of printed drop 56. It will be appreciated that a satellitedrop 48 can land at an edge 134 of printed drop 56 creating a bulge orprotrusion that alters edge 134 can land within the edge 134 of printeddrop 56, or can land outside of printed drop 56.

FIG. 12 shows a top view of another embodiment of an article 130 of theinvention. In this embodiment, a series of printed drops 56 is providedon support 132 of article 130 forming a line 136. In this embodiment,only one satellite drop 48 per printed drop 56 is within a range of 1 to3 printed drop radii R of the centerline of line 136. Such a satellitedrop 48 can land within printed drops 56, along an edge 134 of one ofprinted drops 56, or can land outside of printed drops 56.

FIG. 13 shows a top view of the article 130 of the invention. In thisembodiment, multi-drop structure 137 is provided that is formed fromindividual printed droplets 56 defined on support 132 of article 130 toform a pattern of separated printed droplets 56. A satellite drop 48 canland within a 1 to 3 droplet radii of the center of any printing printeddroplets 56 it will be appreciated that some of the 1 to 3 droplet radiiareas overlap and therefore would result in more than one satellitedroplets landing in any 1 to 3 radii zone. In certain embodiments, thenumber of satellite droplets 48 landing in any one to three radii zoneis limited to n where n is the number of one to three radii zones fromother printing droplets 56 that are within the same one to three radiizone.

It will be appreciated that, in practice, it may be possible foradjacent printed droplets to combine before solidifying and to losedroplet definition. In such a case, the radius described above as beinga radius of the printed droplet can be, for the purposes of thisinvention, one half of the width of the narrowest portion of thestructure formed on the article. Alternatively, a mass of material perunit area on support 132 can be used. In this alternative, a mass perunit area for the structure proximate to a satellite drop 48 isdetermined as X micrograms per squared micrometer. Once this isdetermined, the total mass of satellite drops deposited within a 250micron range of the edge of the structure will typically be less thanabout 12.5% of the product (Xh) where h is the total area occupied bysuch satellite drops 48.

FIG. 14 shows another view of an article 130 having a support 132 with astructure 139 formed thereon from coalesced printed drops. Support 132also has satellite drops 48. Because the printed drops have coalesced,it is difficult to determine the size of printed drops. However, asectional length of a satellite drop 48 outside of structure 139 caneasily be determined by measuring a length of satellite drop 48. In FIG.14, satellite drop 48 is shown as being in a circular form thus, thesectional length can be measured as a radius R. In this embodiment, thetotal satellite drop material on support 132 within a radius of between5 and 50 R is limited to being less than about 50% of the total mass ofstructure 139 within this radius.

Also shown in the embodiment of FIG. 15, is an area 140 between printeddroplets 56 that is occupied by at least one satellite drop 48. In oneembodiment of the invention, the percentage of area 140 occupied bysatellite drop(s) 48 is no greater than 20% to 50% of area 140. In otherembodiments, the mass of satellite droplets 48 located in area 140 is nogreater than 50% of the mass of the printed droplets 56. In still otherembodiments, the mass of satellite droplets 48 located in an area 140 isnow between about 0.5 and 50% of the mass of the mean of the mass of theprinted droplets. In some cases, it is not possible to accuratelydetermine the mass of a printed droplet 56. In such cases the mass ofsatellite drops 48 should not exceed at least 20% of the mass of allstructure within 375 microns of the satellite drop.

It will also be appreciated that while many of the examples providedherein describe an article formed from a single layer of materialapplied by a single pass of the support 130 though a printing apparatusof the invention, the method and apparatus of the invention can beapplied repeatedly to a support 130 to build structures in successivelayers.

Thus, what is provided is an apparatus and method for formingelectronic, optical or other devices using selective droplet depositionfrom a continuous stream of droplets.

PARTS LIST

-   2. substrate-   3. conductor-   4. layer of printed material-   5. layer of printed material-   6. layer of printed material-   7. printed drop-   8. satellite drop-   9. satellite drop-   10. printing apparatus-   11. fabrication apparatus-   12. continuous ink jet print head-   13. continuous ink jet print head-   13 a-13 c. continuous ink jet print head-   14. support-   15. transport surface-   16. pattern source-   17. fluid gutter-   18. pattern processing unit-   19. fluid recycling unit-   20. heater control circuit-   22. nozzle heater-   24. support transport system-   26. transport control system-   28. micro-controller-   30. fluid reservoir-   30 a-30 c. fluid reservoir-   32. fluid pressure regulator-   34. droplet conditioning device-   36. stream-   38. droplet-   39. deflected drop-   40. electrode-   42. gutter-   43. non-deflected drop-   44. nozzle-   46. flow-   48. satellite droplet-   50. print head-   51. fluid-   52. nozzle-   54. heater-   56. printed droplet-   58. non-printed droplet-   60. flow-   62. force-   64. fluid supply-   66. collection vessel-   67. diverted fluid droplets-   68. control surface-   69. reconstitution vessel-   70. patterning mask-   70′. patterning mask-   72. coating-   74. portion-   76. depression-   78. satellite droplet guttering system-   80. OLED-   82. OLED layer-   84. ceramic layer-   86. isolation layer-   90. transistor-   92. support-   94. gate region-   96. spacer-   98. gate insulator-   100. source region-   102. drain region-   104. active semiconductor region-   106. protective layer-   108. interface layer-   110. display pixel-   112. support-   114. layer-   115. gate-   116. insulator-   118. electro-luminescent region-   120. top contact-   122. transistor-   130. article-   132. support-   133. structure-   134. edge-   136. line-   137. multi-drop structure-   138. edge-   139. structure-   140. area

1. An apparatus for forming a structure on a surface, the apparatuscomprising: a fluid source for providing a pressurized fluid to aprinting head; the printing head comprising at least one fluidic nozzle,wherein the printing head provides for the at least one nozzle to emit aflow of the pressurized fluid with satellite droplets and furthercomprises: a droplet forming device for applying energy to the flow offluid adapted to cause the flow of fluid to separate to form a stream offormed printing and non-printing droplets; a droplet deflection devicefor selectively deflecting droplets so that only printing droplets reachthe surface; a gutter to receive deflected non-printing droplets; and asatellite droplet control surface adapted to prevent at least some ofthe material from the satellite drops from reaching the surface.
 2. Theapparatus of claim 1, wherein the control surface comprises a satellitedroplet shield to receive at least some of the deflected satellitedroplets so that the material from the deflected satellite droplets doesnot reach the surface.
 3. The apparatus of claim 1, wherein the dropletforming device comprises a transducer adapted to apply energy to theflow of fluid, said energy comprising heat, ultrasonic waves, mechanicalvibrations, or surface tension modification adapted to cause the flow offluid to separate to form a stream of droplets.
 4. The apparatus ofclaim 1, further comprising a recycling system adapted to receivematerial from the non-printing droplet surface and to recycle thereceived material into a later formed stream of material.
 5. Theapparatus of claim 1, wherein the recycling system further receivesmaterial from satellite droplet control surface.
 6. The apparatus ofclaim 5, wherein the satellite droplet control surface comprises amaterial that absorbs deflected satellite drops.
 7. The apparatus ofclaim 1, wherein the apparatus further comprises a cleaner to apply andremove a solvent to clean the satellite droplet control surface ofsatellite droplets directed thereon.
 8. The apparatus of claim 7,wherein the cleaner carries the solvent and any material therein to arecycling system.
 9. The apparatus of claim 1, further comprising adroplet conditioning device for applying a conditioning energy to aplurality of droplets in the stream.
 10. The apparatus according toclaim 1, further comprising a transport mechanism adapted to providerelative movement of the printhead and surface.
 11. The apparatus ofclaim 10, wherein the surface comprises a flexible support and thetransport mechanism comprises a roller for moving the flexible supportrelative to the printing head.
 12. An apparatus according to claim 1,wherein the droplet deflection device applies an electrostatic ormagnetic potential to the stream for selective deflection of thedroplets.
 13. An apparatus according to claim 1, wherein the dropletdeflection device applies a gas pressure differential for selectivedeflection of the droplets.
 14. An apparatus according to claim 1,wherein the deflection device applies a gas pressure differential to thedroplets, said gas being adapted to condition the droplets.
 15. Anapparatus according to claim 1, wherein the flexible support issheet-fed.
 16. An apparatus according to claim 1, wherein the flexiblesupport is fed from a roll.
 17. The method of claim 1, wherein theprinting droplets are conditioned by the droplet deflecting device sothat a condition of the material in the printing droplets is changed.18. An apparatus for forming a patterned circuit element onto a flexiblesupport, the apparatus comprising: a transport mechanism for moving thesupport past an array of droplet deposition nozzles; a material supplysubsystem for providing a liquid material to each droplet depositionnozzle; with the material supply subsystem comprising: a droplet streamforming means for forming a stream comprising a series of formedprinting and non-printing fluidic droplets of the material, the streamdirected at the support and having satellite droplets therein; adeflector for applying a deflecting energy to separate printing dropletsfrom non-printing droplets in the stream, thereby directing printingdroplets toward the support; a diverting element for divertingnon-printing droplets away from the support toward a gutteringmechanism; and a control surface adapted to control at least a portionof the satellite droplets from the support.
 19. An apparatus accordingto claim 18, wherein at least two nozzles in the apparatus are aimedtoward the same point on the support for simultaneous droplet depositionfrom each of the at least two nozzles.
 20. An apparatus for forming astructure on a surface, the apparatus comprising: a means for providinga pressurized fluid to a printing head; the printing head means havingat least one fluidic nozzle, wherein the printing head provides for theat least one nozzle to emit a flow of the pressurized fluid withsatellite droplets and further comprises: a droplet forming means forapplying energy to the flow of fluid adapted to cause the flow of fluidto separate to form a stream of formed printing and non-printingdroplets; a droplet deflection means for selectively deflecting dropletsso that only printing droplets reach the surface; a gutter means toreceive deflected non-printing droplets; and a satellite droplet controlmeans adapted to prevent at least some of the material from thesatellite drops from reaching the surface.